Objective:To investigate the difference of affective reactions to International Affective Picture System (IAPS) between Chinese and American adults with different culture background. Methods:By using Self Assessment Manikin (SAM), every subject had to complete the Valence and Arousal rating for all the color pictures in IAPS, and the scores obtained were compared between two groups with different cultural background. Results:Among 816 pictures, Valence scores between two groups of male showed significant difference in 70.22%(573/816) pictures (P0.05), and Arousal scores between the two groups of male showed significant difference in 69.61%(567/813) pictures(P0.05). Among 816 pictures, Valence scores between two groups of female showed significant difference in 75.00%(612/816) pictures (P 0.05), and Arousal scores between two groups of female showed significant difference in 63.24%(516/816) pictures (P 0.05). From 9 categories of IAPS, the ratio of positive and negative affective reactions due to facial pictures in two groups of male was greatly different(χ2 =4.857,P0.05), and the ratio of positive and negative affective reactions due to erotic pictures in two groups of female was greatly different (c2=25.93, P0.001). The ratios of low and high arousal due to categories of facial and object pictures were significantly different, and the ratios of low and high arousal due to categories of facial, violence, objects, sports and pollution were significantly different (P0.05). Conclusion:Under different cultural background, the affective reactions of Chinese and American adults towards IAPS are almost similar, but significantly different in the erotic and facial pictures.