Pendulum accelerometer is widely used in inertial navigation systems of aerospace， shipping and other fields. Its assembly operation currently relies mainly on manual operation， making it difficult to ensure product consistency. In view of this， this article has developed an automatic assembly system for a certain type of pendulum accelerometer. Based on the design strategy of macro-micro combination， a micro-motion platform based on a high-precision motion slide table and a macro-motion platform based on a single-axis robot were built. A assembly mechanism was established with the micro-motion platform as the precision adjustment core and the macro-motion platform assisting in pressing and realizing the adjustment of the working positions of different functional modules. At the same time， a three-layer stacked vertical layered structure was designed for the functional modules to ensure precision while avoiding congestion in the workspace. A six-axis collaborative robot and an integrated vision system were introduced to achieve full-coverage recognition and automatic loading and unloading functions in the workspace. Aiming at the influence of magnetic force of magnetic steel parts on assembly accuracy， the method of auxiliary limiting inside the parts was adopted to maintain the assembly accuracy of parts. Based on rigid body transformation， error analysis of the system is carried out and an error compensation model was derived. Experimental results verify that the angle assembly accuracy of the assembly system is better than ±0.03°， the pressing force accuracy is better than ±0.5 N， and the torque accuracy is better than ±0.003 N·m， meeting the assembly requirements and providing strong support for the mass production of this type of pendulum accelerometer.