Negative affect is associated with individual differences in pain catastrophizing (PC). Research suggests that variations in emotion regulation may modify negative affect on PC. Using the process model of emotion regulation, this study examined the relationships of 2 emotion regulatory strategies, cognitive reappraisal and expressive suppression, with negative affect and PC. A total of 224 Chinese patients with chronic pain completed self-report questionnaires measuring pain intensity (the Chronic Pain Grade Questionnaire), emotion regulation (the Emotion Regulation Questionnaire), negative affect (the Positive and Negative Affect Schedule), and PC (the Pain Catastrophizing Scale). Multiple regression models tested the moderating and mediating effects of emotion regulation strategies on the relationship between negative affect and PC. Although both cognitive reappraisal (r=-0.14) and expressive suppression (r=0.37) were significantly associated with PC in univariate analyses (P<0.05), cognitive reappraisal was not significantly associated with PC in multivariate analyses. Multiple regression models failed to show any moderating effects by expressive suppression on the link between negative affect and PC (P>0.05). After adjustment for sociodemographic and pain variables, expressive suppression mediated the association between negative affect and PC (β=0.68, Sobel test: z=3.67, P<0.001). These preliminary findings suggest that expressive suppression of emotion plays a mediating role in PC and subsequent pain adjustment outcomes. More research is needed to further examine other types of negative emotions and different emotion regulatory strategies used in chronic pain adjustment.