The biotransfer of Cry1Ab protein expressed in two transgenic Bacillus thuringiensis (Bt) rice lines, KMD1 and KMD2, in the food chain of Bt rice and its target pest leaf folder (LF), Cnaphalocrocis medinalis (Guenée) as well as the wolf spider (WS), Pirata subpiraticus (Boesenberg et Strand), was analyzed by the method of ELISA. After being fed on KMD1 or KMD2 for 2 days, Cry1Ab could be detected in LF. However, as the feeding time increased, the content of Cry1Ab remaining in LF did not show the tendency of increase. Also, Cry1Ab could be detected in WS by preying on the LF reared on KMD1 or KMD2 for either 2, 4, 6, 8 or 10 days, while their contents were less than those of LF fed on KMD1 or KMD2 for the same time. It was clear that Cry1Ab could be transferred from Bt rice to LF, and then to WS in the food chain by preying, but no bioaccumulation pattern of Cry1Ab was observed. Additionally, there were no significant differences among the predatory consumptions of WS preying on LF reared on KMD1, KMD2 or on the non-transgenic parental rice line Xiushui11. Noticeably, contents of Cry1Ab in the excretion of LF and WS were relatively high. Obvious degradation of Cry1Ab by the crude protease extract from the midgut of WS was found.