The aim of this study was to synthesize, characterize and evaluate of nano composite membrane of polycaprolactone fumarate- gelatin- silicon and magnesium co doped floroapatite for guided tissue regeneration of periodontal tissue. The available biodegradable membranes degrade quickly before complete regeneration of tissue. For fabricating more suitable periodontal membrane which regenerates periodontal tissue and alveolar bone, below procedure was done: at the beginning flouroapatite was synthesized. Then replacement of Magnesium instead of some Calcium and replacement of silicate bonds instead of some phosphate bonds were done. There isn’t any report about addition of silicon to apatite crystalline lattice by mechanical activation method and with cheap silica. Silicon magnesium flourapatite nano particle was selected as the nano particle in the composite. Polycaprolactone fumarate- gelatin membrane was fabricated by electrospinning method. The manufactured polycaprolactone fumarate molecular weigth is 10681 gr/mol, which is very low for electrospinning, so gelatin with polycaprolactone fumarate was used. After doing many tests and invatigating of different electrospinning parameters, 30wt% solution of polycaprolactone fumarate- gelatin in acetic acid was shaped by electrospinning method under below conditio 21 Kv voltage difference, 15 cm distance between syringe and collector. Therafter; 5 and 10 wt% Silicon Magnesium flourapatite nano particles were added to membrane and nano composite membranes were made. Nanoparticles had good distribution in polymer matrix. Membrane with 5 wt% nanoparticle had the best mechanichal properties between membrane with 10wt% nanoparticle and membrane without nanoparticle. Bioactivity and biodegradation of membrane were evaluated. Membrane with 5wt% nanoparticles had less biodegradation than membrane with 10 wt% nanoparticles. No cytotoxicity from membrane was seen in comparison to control sample. Totally it seems nano composite membrane containing polycaprolactone fumarat and gelatin with an equal ratio and containing 5 wt% silicon magnesium flourapatite nano particles is a good candidate for periodontal regeneration. Key words : Mechanical activation, Electrospinning, flourapatite nano particle, Nano composite, Polycaprolactone fumarat, silicon. 1. Introduction Periodontal diseases including the destruction of periodontal ligament, cementum, alveolar bone, and gingiva, often leads to the tooth loss in adults [1]. Guided tissue regeneration (GTR) membrane has attracted extensive attention because a considerable number of teeth can be preserved from extraction in periodontal diseases. The membrane used in GTR technique provides generation of new alveoli and periodontal ligament tissues by isolating the damaged region from surrounding connective tissues [2]. Electrospinning technique is explored increasingly to fabricate fibrous scaffolds from polymers for tissue engineering, which always tries to restore and maintain the biologic function lost in host tissues [3]. Gelatin, which is obtained by a controlled hydrolysis of collagen, has been widely utilized in clinic for its non-antigenicity, favorable absorbability, and cost efficiency [4]. Polycaprolactone fumarate (PCLF) is a cross-linkable derivative of polycaprolactone that has been shown to be a promising material for tissue engineering applications. PCLF has also been used as one component in a wide array of blends for biomaterial scaffolds, from injectable in situ cross-linkable scaffolds, to drug delivery vehicles. The mechanical, thermal, and rheological properties are controlled by the design of the PCLF polymer. For instance, the tensile modulus can vary from 0.87 to 138 MPa depending only on the molecular weight of the polycaprolactone (PCL) precursor chosen [5]. Hydroxyapatite [Ca 10 (PO 4 ) 6 OH 2 , HA], a bioactive ceramic, is widely applied for implanting or repairing bone due to its similarity in chemical composition to the inorganic matrix of bone [6]. On the other hand, existence of trace compounds and elements such as CO 3 - , Na + , K + , Mg 2+ , Cl - and F - in the structure of biological apatite causes the bioactivity of biological apatite to be superior to pure synthesized HA [7]. Silicon (Si) is the essential element for growth and development of the bone, teeth and some invertebrate skeletons. 2. Experimental 2.1. Materials and methods A mixture of phosphorous pentoxide (P 2 O 5 , Merck), calcium hydroxide (Ca(OH) 2 , Merck), magnesium hydroxide (Mg(OH) 2 , Merck), calcium fluoride (CaF 2 , Merck) and