In order to estimate the effect of silt sediment on the lifting force of steel radial gate, a calculating formula was proposed. In the formula, the silt deposited in front of the gate was considered to be the Bingham material which consists of coarse and fine particles. Also, the torques due to grillage sediment weight, rotational hinge friction resistance, seal friction resistance, undersuction effect, door weight and additionalweight were torque etc were involved in the formula. The lifting forces applying on the sluicing steel radial gates in the 2nd and 4th HydroPower Station on the River Xi′er were estimated and compared with those measured in the stations. It was shown that in the case of less sediment deposition, the opening and closing torque on a radial gate is mainly decided by the door and additionalweight, but the lifting force caused from the sediment cannot be ignored. It is the sediment that leads to there is a difficulty in opening gate, thus it should be fully taken into account in the gate design and propose a reasonable operation and maintenance plan for the gate to prevent the event that the gate cannot be opened or closed properly. The accuracy of the calculation formula can meet the needs of engineering practice when it is used to calculate the lifting force of a radial gate with deposited silt in front of it.