Abstract: By means of calculation and comparison of the estimated parameters of cosine model and circular distribution method,the data indicated that the basic calculation methods of both were same and the results of them were equal.Both could be used in the calculation of distribution peak time and the r value,but the calculating procedure of cosine model was more simple than the circular distribution method,the A value and the r value could be obtained from each other.Cosine model could be used in the effectiveness of fitting and estima-tion of disease tendency.The authors suggested that the cosine model could be instead of cir-cular distribution method in the analysis of disease peak period.