Abstract: The number of problems caused by insufficient reliability design of embedded system software is on the rise. How to evaluate software reliability before software delivery has become an urgent problem to be solved. The current software reliability assessment theory originates from the hardware reliability system, and has formed assessment methods suitable for different occasions. However, it is difficult to obtain reliability data during use and the operability is not strong. Code is the essential attributes of software, using the method of software code analysis, proposes a software reliability assessment method based on the code path, using the existing project software test data validate the assessment model, and gives the design method to improve the reliability of software, which can effectively guide the embedded software reliability evaluation and improve the quality of software reliability design.