An improved cosine window is put forward, which can reduce the spectrum leakage and can be easily implemented. The center of the method is to apply an exponent-m-to the usual window function. A proper value can be chosen for the exponent in light of the particular emphasis on frequency resolution, amplitude precision or sidelobe suppression and we can modify the characteristic of the window function through altering the value of m. Cycle of different times is effect.Carried out to implement it in DSP with software. The result of the emluator makes it clear that it is a method with good effect.