This paper explored a new approach regarding social vulnerability to climate change, and measured social vulnerability in three parts: (1) choosing relevant indicators of social vulnerability to climate change; (2) based on the Hazard Vulnerability Similarity Index (HVSI), our method provided a procedure to choose the referenced community objectively; and (3) ranked social vulnerability, exposure, sensitivity, and adaptability according to profiles of similarity matrix and specific attributes of referenced communities. This new approach was applied to a case study of the Yangtze River Delta (YRD) region and our findings included: (1) counties with a minimum and maximum social vulnerability index (SVI) were identified, which provided valuable examples to be followed or avoided in the mitigation planning and preparedness of other counties; (2) most counties in the study area were identified in high exposure, medium sensitivity, low adaptability, and medium SVI; (3) four cities, Shanghai, Nanjing, Suzhou, and Hangzhou were much less vulnerable than others due to their high adaptability; (4) to some extent, there were geographical similarities of SVI, exposure index, sensitivity index, and adaptability index; and (5) the indicator of "Employees in primary industry" related to SVI the most, the indicator of "Renter" related to exposure index (EI) most, the indicator of "Elderly" related to sensitivity index (SI) the most, and the indicator of "Urban residents" relates to adaptability index (AI) most. These results can help decision makers find the focus of their mitigation works, where the efficient of practices will then be improved.