Synchronization is the key process in implementing fault-tolerant computer systems based on voting. There are some problems, such as being hard to design and produce and being less compatible and difficult to use about traditional fault-tolerant computer systems which adopt hardware-based or application program-based synchronizing technologies. Proposed in this paper is a synchronizing mechanism which is based on the system calls in operating systems. The arithmetic of the synchronizing mechanism is described and the implementation in the Linux operating system is introduced. The synchronizing mechanism is transparent to application programs completely and the synchronizing points needn't be set artificially by programmer. The arithmetic is implemented by the combination of hardware and software. Experimental results show that the synchronizing mechanism is feasible and achieves preferably the goals of the system easy to design and convenient to use.