To detect faults of a liquid rocket engine (LRE) turbopump effectively, a turbopump fault detection approach based on rotor intrinsic frequency is presented in this paper. First of all, 28 LRE historical test data were analyzed, from which the values of the first, second and third order critical frequency and the axial intrinsic frequency were achieved. After that, the stability and turbopump fault sensitivity of this four rotor intrinsic frequencies were researched, from which we found that their intrinsic frequency amplitudes had high stability and fault sensitivity. Finally, the turbopump fault detection approach was validated by LRE historical test data. The results show that the turbopump faults can be detected effectively by using the amplitudes of rotor first, second and third order critical frequency as well as axial intrinsic frequency.