A power Control-based Joint optimal for Throughput and Coverage(CJTC) algorithm is proposed in order to balance the conflict between system throughput maximization and coverage optimization in 5G Heterogeneous Ultra-Dense Networks(HUDN). Firstly, the objective function of throughput maximization is derived, and the transmission power of the base station to achieve throughput maximization is solved by convex optimal equation conversion. Then, the objective function of coverage optimization with minimum switching failure rate is derived, and the optimal transmission power of the base station is obtained by iterative joint solution with extension technique. Experimental results show that the proposed CJTC algorithm is superior to other CJTC algorithms in throughput and coverage.