Fuzzing is widely used for browser vulnerability mining,and one of the key factors determining its effectiveness is the test pattern written by the tester.Considering that the test pattern is written with high cost and short survival time,in this article,an automatic construction of fuzzy tester based on pattern-generation is presented.By analyzing the known vulnerability samples and extracting the test pattern automatically,the traditional mutation strategy is then applied to each module in the pattern to complete the automatic generation of the abnormal samples.Experimental results show that in average it takes only 11.168 seconds to finish the automatic construction of 1 089 different fuzzy testers based on 1 089 known vulnerabilities for five browsers,which has much lower time-consumption than that required by testers themselves.Applying on IE 10,IE11 and Firefox 54.0 Web browser with randomly selected 10 fuzzy testers,the new method discovered a total of 57 different bugs,including a high-risk unknown vulnerability.This demonstrates that this method has better capability at finding the unknown vulnerability.