Abstract: This paper discribed a new design of the PCB placement system orien ted to LSI and VLSI. First, components on a board are partitioned according to a fu nction: one of them is partitioned into bus-structured components,such as CPU's, con nectors, etc.,and the o.ther into random structured components. Second, bus-structured circuits are placed by topological algorithm, then the on-bus-structured circuits which are placed by topological procedure are regarded as the secds of constructiveplacement, and placed other components one by one. Finaly, optimum placement isfinished.Thus the placement of all components can be effectively determined.