Abstract: Integrating multi-functional modules into a 3D module is a trend of MEMS miniaturization.A 3D stacked modular package structure of an accelerometer and its modem circuit is fabricated in this article.According to the requirements of modular package,three layers of the stacked module are designed and fabricated on the basis of an accelerometer and its modem circuit.The COB technology based on FR4 substrate is used to assemble devices onto modules,then by being printed through stencil,passive devices` attaching,aligning by a novel alignment tool of vertical interconnection and reflowing,a 3D stacked modular package structure of an accelerometer and its modem circuit is successfully manufactured.MEMS and IC devices are assembled in the same module,high precision（the alignment error is about 0.068mm） stacked alignment of 3×3 modules is complete by the method of alignment bar/via,The vertical interconnection of the stacked module is achieved by being printed through stencil and reflowing once,the average strength of a solder joint is between 30MPa～40MPa,the volume of entire stacked module is about 19×19×8mm³.Factors influencing the vertical interconnection are discussed and shear strength test of the module is presented.