Abstract: This paper focuses on the determination and the character of the objective functions in COCTD(Computer Optimized Circuit Tolerance Design).A single objective function of the tolerance design——the curve of tape-fitting circuit specification function is presented.Further more,the paper discusses the general character of the objective functions and the character at the extreme value as well as the interaction among the variables within the linear,nonlinear and dynamic circuit systems.The common character in the objective functions of the complex circuit systems to be optimized is presented.