To solve the problem of various test items, poor data reliability, complex calculation process and large accumulative error in the energy saving monitoring method of drilling diesel engine, by analyzing and studying the existing torque and speed measurement method and data transmission technology, this paper developed a set of output torque and rotational speed measurement system for drilling diesel engine. The test shows that, the measuring accuracy of the system can satisfy the measurement error range of the diesel engine output torque and speed in the SY/T 5030 “the diesel engine for the petroleum and natural gas industry”. The effect of the system is proved through field test, and that can improve the scientific and accuracy of energy saving monitoring and evaluation of drilling diesel engine.