Tax software has direct influence on the work efficiency and service quality of tax department. How to evaluate objectively and make the correct choice are problems that must be solved in the construction of tax informationization. The comprehensive evaluation system of tax software is firstly designed by its performance factor, developer factor and cost factor according to the industry characteristics of tax work, Then, corresponding evaluation selection method is given which combined by weighted arithmetic averaged operator. The software section of the state taxation bureau in certain city is taken as an example to explain the effectiveness of the evaluation system and method.