Abstract: A software package for computer aided design of control systems consists of sixprograms:management,identification,model analysis and transformation,controllerdesign,simulation and I/O systems.In this paper the identification program IDENT is described which has beendeveloped by Department of Automation at Qinghua University and Dalian Sea Tran-sportation Institute.This program can process three kinds of data from frequency response analyzer,correlation analyzer,and multitrace recorder,frequency response data,impulse res-ponse data and I/O response data respectively.And the IDENT program offers two kinds of models—continuous transfer function G(s) and discrete transfer function H(z).Conversion between the two functionsmay be made through binary linear transform.Some typical examples are included to illustrate the effectiveness of the program.Finally the paper also shows how to use the program in the identification of an elec-trohydraulic servomechanism.