Assembly is one of the most important procedure in manufacturing complex miniature products. Batch assembly is limited by the manual manipulation, for which specially trained technicians is required. In order to automatically assembly certain complex miniature products consisting of multiple parts with different shape and various dimension, and also to reduce the production cost and improve efficiency, an assembly system was developed. Hardware architecture of the system was discussed in detail. Measurement and control strategies in assembling procedure were presented. Local feature extraction and fitting algorithms, reference datum setting were applied to overcome the occlusion. Linear and circular feature fitting from multiple local images of parts, coordinate transformation and the compensation of stages assembly error angle among three local coordinates were adopted to improve the measuring accuracy of vision system. Microscale force sensor was introduced to control the contact force, and the accuracy obtained is less than 1mN. Torque sensor was adopted for sensing the torque during the screw thread assembling, stepping motor and flexible coupler were applied to make the torque smoothly transferred, all of which help precisely measuring and controlling the torque during the M1.4 screw thread assembly.