Aiming at the modulation quality test requirements of 5G NR signal physical layer in modern signal analyzer, and in order to solve the synchronization problem of 5G NR uplink control channel, a synchronization algorithm based on long-cycle prefix search and blind detection of demodulation reference signal parameters is designed by analyzing the frame structure in 5G NR physical layer protocol and the characteristics of uplink control channel. First, the start position of the half subframe is determined by using the long cyclic prefix search, and then the demodulated reference signal is extracted from this position in combination with the time-frequency distribution characteristics, and then the local demodulated reference signal is generated for parameter blind detection. The time slot index obtained from the blind detection further determines the index of the half subframe, thus realizing the determination of the start position of frame. Finally, the signal analyzer is used to collect data and carry out simulation experiments on the algorithm. The results show that the algorithm can effectively realize the synchronization process of 5G NR uplink control channel, and the calculation amount is only 1% of the traditional algorithm.