【Abstract】Obsessive-compulsive disorder (OCD) is characterized by obsessions and compulsions, these symptoms may result from the impairment of information processing or attentional bias for threaten stimuli. Many precedent studies on attentional bias in OCD have yielded conflicting results. The present study aimed to explore the mechanism and difference of attentional bias for negative emotional stimuli between high and low obsessive-compulsive washing tendency individuals. Padua Inventory (Chinese version) was used to select 16 high (upper 10%) and 16 low (lower 10%) obsessive-compulsive washing tendency individuals. Inhibition of return paradigm was used, in which disgust, fear and neutral emotion pictures were used as cues. Stimuli were presented on a Pentium Ⅳ, and participants viewed the monitor from a distance of approximately 60cm. There were 8 pictures for each picture type which provoke disgust, fear and neutral emotion respectively, every picture was presented 3 times as valid and 3 times as invalid cues. Additionally, there were 24 catch trials, summing up to a total of 168 trials in the experiment. In each trial, a fixation cross was presented in the center of the display together with two peripheral boxes, one to the left and another to the right of the fixation cross. 500ms later, participant was presented with pictures provoking disgust, fear or neutral emotion at one of two possible locations. After 400ms, the cue picture was removed and followed by a gap of 50ms before the target dot appeared at the center of one of the two boxes. Participants were instructed to make response to the target, which was presented at the cued location or at the uncued location, as quickly and accurately as possible. Correct target trials were used to calculate mean RTs for each participant and condition. Target RTs were then submitted to a three-way repeated-measure analysis of variance (ANOVA) with cue type (pictures provoking disgust, fear and neutral emotion), cue validity (valid and invalid) as within-subject factors and subjects group (high and low obsessive-compulsive washing tendency individuals) as between-subjects factor. The results showed: (1) The interaction between cue type and cue validity was significant, F (2,60)=26.503，p<0.001. When the target appeared in uncued location, subjects showed slower response following cue provoking disgust and fear relative to following cue provoking neutral emotion，suggesting that high and low obsessive-compulsive washing tendency individuals had attentional bias for pictures provoking disgust and fear, and the mechanism is difficulty of attention disengagement; (2) The attentional bias index for pictures provoking disgust was significantly greater compared to that for pictures provoking fear(F = 29.57，p < 0.001), suggesting that the extent of attentional bias for pictures provoking disgust was significantly higher than that for pictures provoking fear; (3)The differences of attentional bias index for disgust and fear between two group were not significant, it showed that the extent of attentional bias for pictures provoking disgust and fear had no group differences, it was considered to be related with many factors such as the selected pictures, severity of clinical symptoms and the quantity of the participants.