The present invention discloses a method and a device for detecting a primary synchronization signal and generating a sequence in a LTE system, so as to solve the problem that the overhead for 3GPP LTE system to store a local primary synchronization sequence is too much during the initial cell search process. The method for detecting a primary synchronization signal includes: directly generating a local primary synchronization signal sequence with equal amplitude in the time domain as a matched filter; performing a front-end processing for a received signal; performing the matched filtering between the received signal after the front-end processing and the local primary synchronization signal sequence; judging the output amplitude of the signal sequence obtained after the matched filtering; and then obtaining a judgment result of the local primary synchronization signal sequence.