Automation of highly precise microassembly steps will make it easier to realize low cost microsystems. For this, a microrobot-based microassembly desktop station is being developed at the University of Karlsruhe. In this paper, we suggest a common microassembly model for a computer-aided microassembly planning-which is based on geometric reasoning-and discuss its components in detail. The feasibility criteria for the generation of feasible assembly sequences and the optimization criteria for selecting the optimal assembly plan are described. For both these planning steps, the algorithms for an automatic procedure have been developed and implemented. For stations employing several microrobots, a method for decomposition and allocation of an assembly plan is suggested. Finally, we discuss the structure of the station's planning system.