Abstract: The principle of SPIDER signal processing is introduced. An improved SPIDER signal processing method based on discrete spectrum correction is put forward. The signal processing error caused by the inadequate velocity of signal sampling can be overcome by the method. It is found in the testing that in the case of noiselessness, as the adequate correcting points are selected, the agonic correction can be basically achieved; in the case of noise, suitable correcting points should be selected to enhance the noise immunity. The time delay can be obtained by the method while the signalto-noise ratio is inferior. Through the simulation calculation, it can conquer the limit of the spectrometer minimum resolution and measurement range to bring about hurdle effect in the time spectrum, and to improve the measuring accuracy of the time-delay parameter of SPIDER. It is easy to realize the measurement, and can improve accuracy of the system without modification of the equipment. It can be used in the technology of SPIDER.