In order to solve the problems of difficult quantitative filling and poor stability of alkali atoms during the preparation of atom vapor cells, alkali atom vapor cells with different RbN₃ decomposition time were prepared by micro?electro?mechanical system (MEMS) technology combined with photodecomposition of alkali azide, specifically by deep silicon etching, quantitative filling of RbN₃ solution, double anode bonding and ultraviolet irradiation. The atom vapor cells with different RbN₃ decomposition time were tested with a self?built absorption spectrum testing device. The influences of different RbN₃ decomposition time on the Rb vapor absorption peak intensity, half?height width and frequency shift in the atom vapor cells were studied. Though experiments and theoretical analysis, it is found that when the RbN₃ decomposition time is 3.5 h, the Rb atom absorption peak intensity is the largest, which can meet the requirements of high quality atom vapor cell preparation. It provides important technical reference for the preparation of high quality atom vapor cells, and lays the foundation for promoting the development of chip based measurement and sensing technology based on MEMS atom vapor cell.