An adaptive stationary wavelet denoising method is presented for measur ing instantaneous angular acceleration of a crankshaft. The wavelet function is selected by minimizing the energy entropy of wavelet coefficients, the decomposi tion level is determined by checking the variation rate of the wavelet variance,and the method to calculate the threshold of each level is chosen according to the distribution of wavelet coefficients. The proposed denoising method is compa red with the 6 order Butterworth filterer, which is widely used in the instanta n eous angular speed measurement of crankshafts. The results show that if the diesel engine is in normal conditions, two methods have similar performance. While it runs at high speeds, under low loads, and with continuous misfires, only the a daptive stationary wavelet denoising method can preserve local high frequency os cillation signals caused by misfires.