Recently, heart disease such as blockage of blood arteries is a major cause of mortality in the world. In the meantime, a lot of research focused on the development of biodegradable metal stents, such as magnesium and its alloys. Despite the favorable clinical results, low corrosion resistance and high degradation rate of magnesium alloys limit its application for medical applications. The aim of the present study was to prepare and characterize the layer by layer self-assembled coating of Kappa Carrageenan-Chitosan: Heparin on AZ91 magnesium alloy to control the corrosion rate and improve its blood compatibility. In this regard, firstly, the micro arc oxidation (MAO) was performed on the Mg alloy and the process parameters consisting of the electrolyte type, time and voltage were optimized based on X-ray diffraction (XRD), roughness measurement, scanning electron microscopy (SEM) and electrochemical tests. In the fallowing, MAO treated samples were coated with polyethylene imide-Kappa Carrageenan to evaluate the effect of simultaneous two types of surface modification approaches containing MAO process and polymer coating. Afterward, the samples prepared under optimal MAO and coated with polyethylene imide were subsequently coated with 10, 20 and 30 layers of Kappa Carrageenan-Chitosan: heparin. In order to control drug release rates of heparin from coating, the Heparin was loaded in chitosan nanoparticles and applied during the process of layer by layer self-assembled approach. Results showed that 60 V, 30 min and fluorine-contained electrolyte was the optimized voltage, time and electrolyte type for MAO process. As prepared samples consisted of the average pores size 3.32±1.97 ?m, 37% surface porosity and 19.276±1.951?m surface roughness. Moreover, the corrosion current density was measured 0.37 ?A/cm 2 which was significantly less than other samples. Moreover, the formation of bilayer polymer coating on the surface of the sample was confirmed by using Fourier transform Infrared spectroscopy (FTIR). Furthermore, the results indicated that the roughness of surface decreased compared to without polymer coating samples and SEM images showed that the polymer coating covered most of pores fabricated during MAO process leading to to enhance in corrosion resistance. In this regard, the electrochemical tests confirmed the improved corrosion behavior of polymer coated samples due to the filling of the pores and porosity. In this condition, the corrosion current density was about 0.042 ?A/cm 2 indicating 9 times less corrosion compared to MAO-coated sample. Moreover, DLS results and FTIR spectroscopy confirmed the formation of chitosan: Heparin nanoparticles with particle size of 55±10nm. Moreover, FTIR spectra confirmed the formation of Kappa Carrageenan-Chitosan: Heparin coating. Depending on the number of layers (10, 20 and 30 layers), the thickness of polymer coatings were estimated about 2±0.02 ?m leading to enhanced corrosion resistance of Mg alloy. In addition, blood compatibility of coated samples enhanced with increasing coating layers consisting of heparin. Results confirmed that as prepared layer by layer coating had great potential for cardiovascular stent applications. Key words: Magnesium; Kappa Carrageenan; Chitosan; Heparin; Micro arc oxidation; Layer by layer self-assembled coating.