Tobacco whitefly Bemisia tabaci Genn. is a polyphagous pest on many crops. It causes direct and indirect damage to tomato. Tobacco whitefly’s population is changed differently up to crop seasons and climate. In surrouding Hanoi area, the picks of Tobacco whitefly’s population focus on the first half of a year. Population of Tobacco whitefly in the spring-summer tomato season was higher than those in the autumn-winter tomato season. These picks were 1.26-18.57 whitefly/leaf and 0.98-10.96 whitefly/leaf, respectively. Among ecological conditions which influenced on Density fluctuations of Tobacco whitefly, only temperature and rainfall had significant impacts on the development and survive of Tobacco whitefly. Population density of Tobacco whitefly was not significantly affected by investigated tomato varieties and their natural enemies.