Test case design and generation is one key and challenging problem in software testing technology, which essence is how to develop effective test cases based on software specifications. Recently with the maturity and popularity of OO technology, testing based on UML has become an active topic, with some significant results achieved. Aimed to the interactive characteristics of most business process software systems, this research is devoted to the study of test case design and generation method based on UML activity model. First of all, this paper gives a simple introduction of UML and model- based testing technology, points out advantages of applying UML models to direct testing, then analyzes UML activity diagram models, their testability and test strategy. And point out UML activity diagram is not only a powerful model in requirement analysis and design, it can also be an important basis for software testing. Secondly, we make a description and analysis to the business process, introduce the features and requirements of business process testing, and then introduce the intelligent algorithm-ant colony algorithm, and proposed a anti-ant-like agents algorithm based the ant colony algorithm. Based on above analysis, this paper is focused on the approach of business process test case generation based on activity model. Related definition and technology are brought out such as test case and test scenario, then the test case generation strategy is put forward. In test scenario generation part, we use the modified ant colony algorithm-anti-ant-like agents algorithm.