One of the challenges of using Stainless Steel 316L (SS316L) as an implant substrate is poor adhesion of organic/inorganic coatings on their surface. Poor adhesion of the provided coating may lead to serious problems like blockage of arteries in cardiovascular stents. In this study, the (3-aminopropyl) triethoxysilane effect as an adhesion promoter between the organic/inorganic polyhedral oligomeric silsesquioxane - poly(carbonate-urea) Urethane (POSS-PCU) coating and substrate was investigated. The objective was to study the significant parameters, including the surface preparation method, pH of the silane layer, and the curing process on adhesion of the coating on the SS316L.Contact angle measurements indicated that the higher surface free energy values attributed to the pretreated silane layer did not result in better adhesion strength of POSS-PCU coating. Scanning Electron Microscope/Energy Dispersive Using X-Ray and Atomic Force Microscopy results revealed that more uniformity was obtained in silane layers prepared at pH= 4 (acidic solution) compared to higher pH values. The ellipsometry results showed that the acidic silane solution, which was cured at high temperature, had a lower thickness than other primer layers. Lap-shear strength results confirmed a noticeable increase in the adhesion strength of POSS-PCU coating on the SS316L substrate in the presence of the silane layer in dry and wet conditions.