Tool life is an important index to judge machinability of cutting tool. Wear standard is a necessary considered factor to give tool life. Microwave printed board is composite material, wear standard should be found by tool wear experiment under definite machining environment. Life-span data of cutting tools with different combination of cutting parameters is collected through machining experiment. And then based 2 mathematic models: extended Taylor empirical equation and quadratic response surface equation, with regression analysis method, the mathematical models of relationship between cutting parameters and tool life were given respectively. Through comparison of two regression methods, response surface equation based wear equation is given, determining calculating method of tool life for High-speed Machining of Aluminum Base Microwave Printed Circuit Board. Described method can be popularized according to change of machining conditions.