[Aim] Both melon and cotton are preferable hosts of Bemisia tabaci and Aphis gossypii. The growing system of melon intercropping with cotton offered a favorable condition for the mixing of these two pests. It was studied in this paper that which one will take advantages in this competitive situation. [Method] Population dynamic and competitive interference behaviors of B. tabaci and A. gossypii in the growing system of melon intercropped with cotton were studied in Turpan under field and indoor observations. [Result] In 2011 and 2012, the occurrence of A. gossypii on both cotton and melon are earlier than that of B. tabaci, however the interferences and competitive effect of B. tabaci against A. gossypii are significant along with the increase of B. tabaci population. Thereafter, B. tabaci became to the dominant population in the field from later August to early September. Indoor behavior observation showed that B. tabaci always took advantages when competing against A. gossypii. The main behaviors included driving A. gossypii away with antenna and legs, and entering the area where A. gossypii was located to disturb. The interference behaviors were less intense when both A. gossypii and B. tabaci were less than 4 per vessel, whatever A. gossypii or B. tabaci was firstly introduced into the vessel. However B. tabaci drove A. gossypii away with antenna and legs more frenquently than when they were over 8 per vessel. Regarding the settled time of A. gossypii or B. tabaci was firstly introduced into the vessel, the disturbances declined over time. [Conclusion] Thus, B. tabaci was a superior competitor to A. gossypii in the growing system of melon intercropping with cotton.