The measurement data of the navigation sensor commonly includes lots of noise. Aim to ensure planes flying safely and stably, the method that how to decreasing noise is important. This paper introduces theory of wavelet transform, and proposes the method to decrease noise in measurement data of the navigation sensor based on wavelet analysis according to the multi-resolution analysis characters of the wavelet transform. By means of Daubechies wavelet function and using threshold decreasing noise method, this paper analyses the off-line positioning data of the navigation sensor. Through the engineering application, the method is integrated and validated in a navigation sensor.