The invention provides a turbine generator rotor winding fault diagnosis method based on a diagnosis model and a turbine generator rotor winding fault diagnosis device thereof. The method comprises the steps that multiple equivalent conductors of corresponding rotor windings and the fault matrix of the rotor windings are constructed according to the rotor parameters of a turbine generator, and a transmission line equation of the rotor windings in the fault-free state and the fault state is established through a multiconductor transmission line method; and a fault diagnosis model is established by using the transmission line equation in the fault-free state and the fault state, and fault diagnosis is performed on the turbine generator under diagnosis by using the fault diagnosis model. The more accurate fault diagnosis model is established based on the multiconductor transmission line method so that the accuracy of fault diagnosis of the rotor windings of the turbine generator can be enhanced.