Through a systematic field survey, olfaction testing, and free diffusion observations in both of cages and petri dishes, the behavior and partial mechanisms of host selection of Bemisia tabaci Gennadius were investigated on different host plants. Our results showed that the whitefly was obviously characteristic in host selection. To different host species, the whitefly showed intensive preference for eggplant, cauliflower and cucumber, but non-preference for water spinach, celery and amaranth. The host selection was also observed among different cultivars. Moreover, we found that plant color was a factor determining host selection for B. tabaci. Although whiteflies did not make response to a single host plant placed to their vicinity, they could be attracted by ethanol extracts of host leaves, suggesting some chemicals in host leaves might also contribute the host selection. When the diffusion of B. tabaci from the source to host plants was observed in cages, we found that the numbers of B. tabaci landing on the surface of host leaves were greatly different among hosts and among cultivars during the period of free diffusion, and the population of B. tabaci on host leaves continuously changed within certain time range after this period.