Based on a detailed investigation of a variety of current software test models, a novel behavior-based software test model is first proposed. It includes several activities, namely test design, test plan, test case generation, test execution, test result analysis and test reuse. And they are laid out in the whole lifecycle of software development process. Then the model is intentionally applied to a large software test application project which is called American on-line as early as possible. The practical result shows that the software test model has a good bug-mining operation and can generate test cases efficiently in the regression test.