In this paper, we propose a scheduling method for synchronous communication between threads in the Bach hardware compiler. In this method, all communications are extracted from a behavioral Bach-C description and statically prescheduled to synchronize communications between threads if possible. Then all the operations and communications of each thread are synthesized independently according to the prescheduling result. Consequently, we can synthesize large system LSIs efficiently, because we do not need to synthesize the whole system descriptions at once to synchronize communications. Experimental results show that our method improves throughput of synthesized circuits and is applicable to large systems designed with the Bach hardware compiler.