By means of the contrast observation evaporation data from E 601B and the small sized evaporator data from 1985 to 2001 during the unfrozen period (April to October) at Tacheng National Standard Climatic Station and the contrast observation evaporation data from 2009 to 2011 during the frozen period (November to March) from the Tacheng Hydrological Station, the conversion coefficient is acquired by the ratio method and the multiple linear regression analysis method. Results show that the data arrays from contrast observation evaporation appear linearly correlated.The correlation coefficient is 0877 in the unfrozen period and 0924 in the frozen period. The conversion coefficient is 0596 in the unfrozen period and 0349 in the frozen period. It provides important basis for using long sequence single observation data of small sized evaporation pans.