Abstract: In order to solve the problems of high sidelobe level and signal-to-noise ratio of pulse compression for linear frequency modulation signal with small time-bandwidth product, a new method to design optimized mismatched filter is proposed. In this method, peak-sidelobe level, loss of signal-to-noise ratio and main-lobe widening are jointly controlled, and optimized mismatched filter is designed using convex optimization algorithm to achieve lower peak-sidelobe level under lower loss of signal-to-noise ratio, with wide Doppler tolerance simultaneously. This method is demonstrated to be effective by computer simulation, which shows that the new optimized mismatched filter can get much better sidelobe suppression effect and signal-to-noise ratio compared with the Hamming window method,and can primely meet the requirements of engineering application.