The dynamic pressure relief quality of the pilot oil pressure directly depends on the resistance of the internal flow channel of the security manifold in the electro-hydraulic regulating system of low-pressure steam turbine.The flow field characteristics of three π channel module units,T-type orthogonal and non-orthogonal channel module units and right angle crossing and sudden expansion characteristics channel module unit in security manifold were analyzed by CFD simulation,and flow-pressure loss characteristics were compared,a simple method for predicting the complex channel resistance in manifold block was proposed.It is shown that the pressure loss can be reduced by appropriately increasing the curvature radius of the liquid flow in the right angle turning channel;under the same flow rate,the pressure loss of the channel module unit with the characteristics of right angle crossing and sudden expansion is the largest.