介绍计算异步电动机电磁转矩的精确方法及电磁转矩在斜井提升系统故障诊断中的应用。对异步机的高度非线性模型进行坐标变换，使其转变为线性模型；在新坐标系下，给出计算转子磁通、电磁转矩的精确方法。构造了一个拟专家系统的知识库并运用在线计算的电磁转矩设计出一个掉道故障诊断系统。最后给出了现场运行的测试结果。 An accurate method of calculating the electromagnetic torque of induction motor and the application of electromagnetic torque in fault diagnosis of inclined shaft hoisting system are introduced. The highly nonlinear model of asynchronous machine is transformed into a linear model by coordinate transformation. In the new coordinate system, an accurate method of calculating rotor flux and electromagnetic torque is given. Constructed a knowledge base of the expert system and designed an out-of-road fault diagnosis system by using electromagnetic torque calculated online. Finally, the field test results are given.