The trunking systems based on TD-SCDMA network are limited by the interference that users create to each other.Conventional power control algorithm cannot eliminate adjacent group interference.The beamforming was used to suppress the interference outside the main lobe,the joint detection of multiple groups was conducted to remove both intra-group and inter-group Multiple Access Interference(MAI) in the lobe for the uplink receiver,then the two-step iterative power control algorithms were combined with joint detection to eliminate effectively the interference in the system,thus reducing system requirements on power control and improving the performance.The simulation results validate that the algorithm can effectively reduce the system transmission power and to suppress the interference.