Causal map is an effective method of software testing, suitable for a wide range of conditions described in the portfolio, with a number of test cases produced from the corresponding forms of action. Causal map is finally converted to the determine table, but the conversion from the causal graph to the determine table is very difficult. This paper describes the principle of Causal mapping, presents a detailed description of the Causal map to determine meter conversion algorithm, and introduces the causal mapping methods to generate test cases.