Abstract: The defects of the present methods in researching the function using magnetizing water to strengthen concrete were analyzed and then the method to quantitatively detect the influences of magnetizing water on cement’s vigor by using “activity coefficient” was presented. The influence of the length of magnetization path on the result of magnetizing water was considered for the first time, and the influence of different factor on cement’s vigor was investigated through the orthogonal experiment. Besides, the interaction effects of the factors was considered and the factors relativity was analyzed, and further the optimum matching programs was found. The results showed that the given method is more scientific, more convenient and more direct, and can be used in investigating the strengthen function of magnetizing water on the cement concrete