In order to overcome the "frequency ambiguity" phenomenon by using the traditional Fast Fourier Transform to analyze signals of equipment under the condition of varying rotating speed, this paper presents an order analysis method without phase signal. Firstly, the variation range of rotation speed is estimated by equipment control system or other ways to confirm the filter range; secondly, narrow band filtering is filtered off from the signals; Thirdly, the instantaneous frequency is calculated by Hilbert Transform; Finally, the stationary signal in angular domain is obtained by resampling the timedomain signal according to instantaneous frequency, and then the order spectrum is made by Fast Fourier Transform. The validity and accuracy of the order analysis method are verified by the simulation signal. Then, the method used to extract the amplitude of sinusoidal component of signal under variable rotating speed condition is applied in analyzing equipment signals in UAV, laying a foundation for accurately setting up the environment condition of equipment. The method in this paper is an effective supplement to the signal order analysis, and its application has reference value for the evaluation of dynamic environment of similar equipment.