The relationship between T. castaneum and S. zeamais was studied through reciprocal selectivity experiment, single rearing and mixture rearing at 30 ℃, 75% RH. The results showed that the mutual selection behavior between the two species was not obvious in the same ecological environment. The number of T. castaneum adults in the population decreased first, then increased slowly with increasing treatment time, the maximum number of adults in the population reaching 11.5 times of the initial number after 56 d rearing alone in wheat. while the number of S. zeamais adults in the population increased obviously with increasing treatment time, and reaching 53.9 times of the initial number after 56 d rearing alone in wheat. Compared with rearing alone, the number of adults in the population of both T. castaneum and S. zeamais significantly increased under mixture rearing in wheat, the maximum adults in the population reaching 20.3 and 93.4 times of the initial number respectively after 56 d. Therefore, both T. castaneum and S. zeamais are important pest insects during wheat storage, and the S. zeamais infestation can promote the growth of T. castaneum population.