In this paper, we analyze the features and distinctions of 6 classical algorithms: greedy algorithm (G), greedy evolution algorithm (GE), heuristics algorithm (H), greedy heuristic G (GRE), integer linear programming algorithm (ILP) and genetic algorithm (GA) to ensure the main influencing factors-the performance of algorithms and the running time of algorithms. What's more, we would not only present a research design that aims at gaining deeper understanding about the algorithm classification and its function as well as their distinction, but also make an empirical study in order to obtain a practical range standard that can guide the selection of reduction algorithms. When the size of a test object (product of test requirements and test cases) is smaller than 2000×2000, G algorithm is the commonly recommended algorithm. With the growth of test size, the usage of GE and GRE becomes more general.