Abstract: Software testing is the basis of ensuring software quality, and unit testing is one of the most important sections. Aiming at the current situation of railway signal software, such as increasing scale, gradually complicating form and insufficient unit testing, this paper analyzed the importance of software unit testing and common methods, expounded the basic requirements and test steps of the software unit testing for railway signal. Combined with the specific practice of the software unit testing of the section integrated monitoring system, the paper put forward a set of complete unit testing method, which could effectively avoid errors, thus ensure the stability and reliability of the railway signal software.