Abstract: Using yellow sticky trap, the seasonal fluctuation of adult population of Bemisia tabaci was investigated in vegetable area of Linhai between Feb. 2006 and Feb. 2007. This investigation showed two occurrence peaks of adult population of the whitefly a year, one occured between spring and summer season and the other in autumn. Eight models were established according to the population feature and its correlation with climate and agricultural factors. Simulation analysis showed that prediction of these models was in the range of 60.9% coincident with the invistigation. The population levels of adult whitefly based on ten days a year could be predicted with these models and thus the early warning could be made according to the model simulation.