The invention provides a method for improving distance measurement precision of a responder and aims to provide a simple and reliable method for improving downlink frame synchronization trailing edge pulse precision. According to the method, in a noncoherent mode, after an uplink signal is received by the responder, the uplink frame synchronization information is extracted after de-spreading, demodulation frame synchronization processing, an uplink frame synchronization signal is sampled by utilizing the downlink frame synchronization trailing edge pulse, the sampling value after re-framing is sent to a ground station through a downlink, and distance measurement is carried out by the ground station through calculating time delay between sending frame synchronization and receiving frame synchronization. The method for improving distance measurement precision of the responder is advantaged in that the compensation function is realized through programming in an FPGA chip of a responder hardware platform, a system clock of the responder is used as a modulation clock of the downlink, a 32-bit frequency control word accumulator DDS is utilized to generate a code sending clock, and the code sending clock is utilized to generate the downlink frame synchronization trailing edge pulse.