The invention relates to a Fuzz optimization method based on a file format. The method includes 1, configuring original sample files, a target program to be tested and Fuzz thread parameters in testing environment; 2, inserting a file format analyzing module used for analyzing the format of the sample files; 3, performing Fuzz operations on the analyzed sample files and storing results to a local storing unit used for calling the target program to be tested; 4, under the set Fuzz threads, executing the target program according to sample file parameters in the storing unit, and recording abnormal information produced in the process of executing the target program; 5, traversing all the sample files in the storing unit to complete all tests till all the sample files are tested. Selections of Fuss positions have strong correlation with the specific file format of the sample files, production of the Fuss data has strong pertinence with the specific type of each domain of the sample files, and efficiency in excavating software vulnerabilities can be high.