The purpose of this study was to examine the effects of a Mindfulness-Based Stress Reduction (MBSR) program on reduced stress and perceived anxiety. 27 students with social anxiety, aged 16–40 years, from a China university were randomized to MBSR with routine care group (MBSR group, n = 14) and routine care group (non-MBSR group, n = 13). As expected, an increase in anxiety symptoms during the social situations led to more perceived anxiety in the non-MBSR group, but not in the MBSR group, due to the MBSR program. However, the MBSR group had significantly decreased anxiety and avoidance symptoms compared to the non-MBSR group. The results in this trial show that MBSR can protect students with social anxiety from an increase in perceived anxiety during the social situations.