This paper presents a sorting method based on cosine weighting to improve the anti-jitter ability of histogram algorithm in radar signal sorting. This method uses variable and superposed boxes, into which the collected radar pulses repetition interval (PRI) falls, and the histogram increment of these boxes are normalized weighted by cosine window smoothly. Each peak position of the histogram that exceeds threshold is the estimated PRI of radar. The histogram obtained by this method is smooth and the peak is clear. Furthermore, the sub-harmonic is well restrained. Experimental result shows that this method has good anti-jitter ability.