Wet bulb temperature is an important parameter in some largescale engineering design and safety, and a key factor in investment costs and operational effectiveness. Since wet bulb temperature observation stopped, it is pretty important to solve how to get more accurate data and study the continuity. Therefore, based on the hourly and timing data of 70 stations in Jiangsu Province, the Newton iterative method and the best approximation method are used to study the variance calculation and data continuous application. The best approximation method is better with high accuracy, and good compliance rate (90.8%-100%), which is far higher than that of the Newton iterative method (12.7%-20.1%). And the results present an obvious diurnal variation that the coincidence rate is the higher during 09:00-20:00 BT, but lower before and after sunrise. The analysis of the 40year series shows that the calculation results of the best approximation have a good stability, and to a certain extent, could replace the observed value. The effect is better when temperature is high and vice versa. Compared with the heterogeneity in the decade data, research on the continuity of the wet bulb temperature data is more reliable.