In a laboratory test, Bemisia tabaci on the plants of three transgenic Bt cotton cultivars (GK12, 33B, and SGK321) and their non-transgenic parents (SM3, 33, and SY321) was used for feeding Propylea japonica. The effects of B. tabaci on the growth and predation of P. japonica were studied. Meanwhile, the olfactory and visual reactions of P. japonica to B. tabaci from the leaves of these transgenic and non-transgenic cotton plants were observed using a Y-shape olfactometer. The transgenic cotton plants and their non-transgenic cotton parents didn't produce significant effects on the developmental duration and survival of P. japonica. There was no significant difference in the visual reactions of P. japonica to cotton leaves, the nymph, honeydew, exuviates of B. tabaci. The olfactory reaction of P. japonica was descended in the order of nymph, exuviates, cotton plant, and honeydew. P. japonica on the three non-transgenic cotton plants had higher olfactory selectivity for the nymph of B. tabaci than those on the three transgenic cotton plants. P. japonica on the two univalent transgenic cotton plants of GK12 and 33B had lower olfactory selectivity for the exuviates of B. tabaci than those on their two non-transgenic cotton plants of GK12、33B. There was no difference in the olfactory selectivity for he exuviates of B. tabaci on the bivalent transgenic cotton SGK321 and its non-transgenic parent SY321. When the prey density was greater than 200 head/dish, the amount of B. tabaci predated by P. japonica was higher on transgenic cotton plants than on non-transgenic cotton plants. When the prey density was lower than 200 head/dish, the amount of B. tabaci predated by P. japonica was higher on non-transgenic cotton plants than on transgenic cotton plants. The predation of P. japonica to B. tabaci was in conformity with Holling Ⅱ type reaction. The theoretical limit and the instant attack rate of P. japonica on B. tabaci were significantly on transgenic cotton plants than on their non-transgenic cotton plants.