Glass ionomer cements are of important restorative materials used in dentistry. Improvement of biological and mechanical properties of these materials has consistently of interest to researchers. The aim of this study was to improve the strength, bioactivity and Fluoride release of glass ionomer cement by adding the ceramic nanoparticles to it. For this purpose, the ceramic component of glass ionomer cement was prepared with sol-gel and melting methods. Hydroxyapatite, Fluoroapatyte and bio glass also were synthesized by sol-gel method. Then, the synthesized ceramic nanoparticles and purchased Titania nanoparticles with the amounts of 2.5, 5 and 7.5 wt.% were added to glass ionomer powders. Poly acrylic acid was used as binder. Phase, morphological and microstructural investigations were performed by X-ray diffraction (XRD), X-ray florescence (XRF), scanning electeron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The mechanical properties of produced samples were evaluated by compression test. In order to assess the bioactivity of nanocomposites, the samples were immersed in simulating body flouid (SBF) for 14 and 28 days. SEM was used to confirm the formation of apatite layer on immersed specimens. Finally, the fluoride release tests were carried out in artificial saliva fluid, so that the specimens were immersed in the fluid for 1, 3, 7 and 14 days and the amount of released fluoride was measured by potentiometric method. The results demonstrated that the glass ionomer, bio glass, Hydroxyapatite and Fluoroapatyte particles synthesized by sol-gel method have nano size dimensions. Atomic absorption and SEM tests confirmed the formation of apatite layer on all composite specimens. According to compressive tests results, the maximum strength was obtained by adding 2.5 wt.% of ceramic nanoparticles to glass matrix. By adding this amount of Fluoroapatite, Hydroxiapatite, Bio glass and Titania to the glass ionomer matrix, the compressive strength was improved by 33%, 44%, 19% and 68% respectively. These results showed that Titania nanoparticles had a greater effect on strength improvement. The nanocomposite sample containing Fluoroapatite nanoparticles exhibited the highest bioactivity among the produced nanocomposites. The results of Fluoride release tests indicated that Fluoroapatite nanoparticles increase the rate of Fluoride release. Keywords : glass ionomer, bio glass, biological nanoparticles, compressive strength, bioactivity, fluoride release