Sexual stimuli provoke both sexual arousal and disgust, and the coaction between these emotions determines sexually behavioral outcomes. The current research includes two experiments to explore the bidirectional relationship between sexual arousal toward erotic stimuli and disgust induced by sexual body fluids. Study 1 presented 234 participants (117 women) with sexual body (vs. neutral) fluids followed by erotic stimuli, and Study 2 presented 235 participants (117 women) with erotic (vs. neutral) videos followed by sexual body fluids (and a non-sex-related stimulus). Study 1 showed that exposure to sexual body fluids reduced sexual arousal and the likelihood of sexual engagement toward erotic stimuli in participants with high sexual disgust sensitivity but increased sexual arousal and the likelihood of sexual engagement in participants with low sexual disgust sensitivity, while Study 2 suggested that men exposed to erotic (vs. neutral) stimuli reported lower disgust, stronger sexual arousal state, and higher willingness to interact with the sexual body fluids. There was no relationship between subjective feelings of sexual arousal and disgust in these experiments, while the balance of sexual arousal and disgust toward sexual body fluids and erotic stimuli had a positive association. Also, exposure to erotic stimuli had no effect on reactions to generally disgusting stimulus, but feelings of sexual arousal toward erotic stimuli were positively associated with disgust induced by generally disgusting fluid. These findings suggest that Behavior Immune System regulates disgust to establish a balance between benefit and cost related to sex as well as provide insight into the process underlying sexual dysfunctions.