Abstract: Aiming at the problem that the target detection system based on continuous-wave has a weakness in anti-jamming capability and does not make full use of target signal features, a method of target signal recognition based on envelope increasing rate of echo signals and its change tendency is proposed．The method divids a typical target signal envelope curve into three parts such as exponential rising part，linear increasing part and growth saturation part．The different parts of the curve are distinguished by the characteristics of envelope increasing rate and its change tendency． Sliding data window polynomial fitting algorithm based on Lagrange multiplier is used to smooth the target signal envelope curve sampled by experiments．The envelop increasing rate and its change tendency are calculated by difference quotient algorithm．Calculation results of examples show that the recognition rates of the method for exponential rising part，linear increasing part and growth saturation part are 88.2%,82.7% and 91.3% respectively.