A new radar signal, the chaotic based random stepped frequency signal, is proposed because of characteristics of chaos such as pseudorandom behavior, sensitivity for initial condition, accessibility for generation and control, and easy realization and processing for the stepped frequency signal. A signal model was introduced, then the ambiguity function and the cross correlation function were analyzed theoretically in detail, and two different echo signal processing methods were proposed finally. Numerical simulations based on four typical chaotic maps and two random series show that the designed signal is effective, and promising for radar application.