Abstract: In order to eliminate the possibility of man-made faulty operation in the process of pig launching/receiving of crude oil pipeline, a new valve interlock method is introduced in this paper. Different from using electrical equipment to interlock in the past, this method significantly saves the cost and decreases the complexity of the operation without addition of any hardware. The ESD function of limitorque used in pump stations of Mohe-Daqing Crude Oil Pipeline is put into service combined with the PLC software system. Setting the priority level of ESD above the in situ level, connecting the line, the PLC procedure is completed. The bypass valve and the main valve are operated according to the operation procedure of technological requirements. Otherwise the valve order can not be executed. Thus, the valve interlock in an in situ state is realized to avoid the operational risks caused by man-made faulty operation.