Autofocusing technique is one of the key technologies to ensure the high quality image for the optical measurement system. An algorithm of rapid autofocus combining rough and fine adjustment is proposed. This method can automatically search the focal plane by evaluating the image definition. First, the image edge function based on the improved Kirsch operator with high performance is used to rough focusing. The evaluation function based on wavelet transform is used to fine focusing in narrow range later.Ununiform sampling function is used as the method calculating the focusing window, which can reduce the work of the data processing and the calculating time. An improved mountain climbing searching algorithm and tactics of the optimum focus position, which can significantly accelerate the search speed. The experimental results indicate that this algorithm can meet the focusing requirements of the optical measurement system, which can obtain good practical value.