Abstarct: Wavelet experiment and analysis is a new method to solve problems in mathematics, physics and engineering. Wavelet decomposition is often used in wavelet signal processing. So that the wavelet transform of a function, as the Fourier transform, is a powerful tool for analyzing stationary phenomena. In this thesis, Haar wavelet method use to calculate a set of ordinary and partial differential equations. in which we solve and investigate ordinary and partial differential equations by using the Harr wavelet function, then we compare the results with the exact solutions.