Several methods are presented for the determination of accumulative amount of precipitation at a single location by means of Z-I relations,such as raindrop size spectra, Z_r-I_g, mean of value A and mean value of A. Data from the three processes of precipitation in 1981 were used to determine Z-I relations and verify the data obtained on June 24 and July 9, 1980.It is found that the accuracy of these methods are quite satisfactory.If only the accuracy in measuring I and Z can be improved and the Z-I relations classified according to the type of rainfall after the value is properly chosen for b in the relations, greater accuracy of the last two methods may be achieved.