A joint power control algorithm based on current link information was proposed to address the shortcoming of the conventional power control algorithms for CDMA (code division multiple access) TDD (time division duplex) system. The joint power control equation was deduced in theory. In the new algorithm, the power adjustment of all UEs (user equipments) was derived jointly from the common network resource. The adjust of transmission power all UEs assigned in the same time slot was based on current information, which took into account the power adjustment of other UEs in next step. The goal is to allow UEs to share network resources equally so as to speed up the convergence of power control. A function model was developed to verify the new algorithm and evaluate its performance. The simulation results indicate that the new algorithm outperforms the conventional algorithms in terms of smaller standard deviation of receiver SIR (signal-to-interference-ratio), lower system interference, higher energy efficiency, and thus better system capacity.