In the present study, we showed evidence of an integration between two unconscious semantic representations. In experiment 1, two masked Chinese words of the same or different categories ("orange apple" or "grape hammer") were simultaneously presented in the prime, followed by two Chinese words also of same or different categories in the target. We examined possible prime/target visual feature priming, semantic category priming and motor response priming effects. Moreover, two ISI intervals (53, 163 ms) between the prime and the target words were used to examine the positive and negative priming. The results revealed a "negative" motor response priming and a "positive" semantic category priming effect independent of the ISI when the target words were of the same category. Experiment 2 eliminated an alternative interpretation of the effect based on different number of category words changed across the prime and the target. Experiment 3 eliminated a potential confound of unequal numbers of trials for motor congruent and incongruent conditions in Experiment 1. Overall, these results indicated an integration between the meanings of the two subliminally perceived words in the prime. The difference between simultaneous and sequential presentations, and the reason why positive priming was not observed when the interval between the prime and the target was short were discussed in the context of unconscious semantic integration.