Abstract: Abstract: A fully three-dimensional numerical model is used to numerical simulation of condenser cooling water flow characteristics, and then research on the movement of the condenser flow field and flow resistance characteristics, comparing with the theoretical results on the design manual. Researches show that: Water among condenser pipes flow in three layers of water condenser and flow vortex exist in the cross-sectional area mutations, making mechanical energy loss be bigger; Due to the condenser pipe friction loss and the vortex exists, 3 three layer pressure reduces step by step and the condensing tube pressure drop the largest, 59.44%; Simulation of condenser water resistance is 91.26 kPa, and manual result is 90.05 kPa. Two results are closed, and the error is only 1.4%, proving the correctness of the numerical simulation method. Using numerical simulation method can optimize the structure of condenser and to improve the cooling efficiency.