The invention discloses a real-time evaluation method for the health state of a wind turbine unit. The method comprises the steps that firstly, on the basis of historical running data of the wind turbine unit, running work condition dividing of the wind turbine unit is achieved by applying a clustering technology, and standard state cloud models of the wind turbine unit under all work conditions are calculated; secondly, work condition identification is conducted on real-time data stream of the wind turbine unit through a stream-type clustering algorithm, and cloud models of the real-time states of the unit are calculated; thirdly, deviation values between the cloud models of the real-time states and the standard state cloud models are calculated and taken as health indexes of the wind turbine unit; lastly, the health state of the wind turbine unit is evaluated according to the magnitude of the health indexes. According to the method, the running states of the wind turbine unit are described through the cloud models, the health state and the development tendency of the wind turbine unit are acquired by introducing a time window method, therefore, the uncertainty of state monitoring information of the wind turbine unit is fully taken into account, the accuracy of an evaluation result is greatly improved, and powerful support can be provided for making a wind turbine unit maintenance plan.