Abstract: For improving forecasting and sustained control the level of harm, dynamics of Bemisia tobaci (Gennadius) on different protected vegetables was monitored by using yellow sticky cards from 2009 to 2012. The results showed that internal cause of population and external cause of climate had a synergistic effect on the pest dynamics, leading tobacco whitefly to fluctuate up and down. The pest’s population had two damage peaks, summer and autumn peak (from July to August and from September to October). There were significant differences in population size among years. Both 2009 and 2010 were the severe occurrence period, while both 2011 and 2012 were lighter occurrence period compared with the other years. There was significant difference in catches by yellow sticky cards between different protected vegetables. The catches on cucumber was the highest, followed by eggplant and tomato, and the catches on pepper was the lowest. This suggested that the preference order of the pest on the protected vegetables was cucumber> eggplant> tomato> pepper in Hangzhou Area. Based on analyzing historical data, the population cardinal number in different periods and the meteorological data (such as temperature, humidity, illumination etc.) were used in selecting forecasting factors to construct the occurrence period forecasting model and occurrence amount forecasting model in peak period. In total, twenty- nine factors including nineteen meteorological factors and ten population density factors were screened out and used in the models, and models for different protected vegetables were constructed with the methods of stepwise regression. The population cardinal number and temperature were two key factors influencing the pest’s population dynamic based on the models.