Research regarding the regional environmental regulation efficiency (ERE) and influencing factors can provide theoretical guidance for regions to improve their ERE effectively. By employing a two-step approach, the data envelopment analysis (DEA) CCR-BCC model is built with the inclusion of scale changes, and a Tobit model is developed to explore the influencing factors for the regional ERE, followed by an application to analyze the spatiotemporal variations of ERE in Jiangsu province from 2005 to 2015. It is found that in time dimension, the ERE lies generally in a weak effective interval of [0.5, 1) and displays a shock upward trend. In the spatial dimension, the ERE presents an obvious "bilateral effect", namely, the efficiency is high for both the southern and northern of Jiangsu province but lower for the middle area. Besides, GDP per capital, industrial structure, trade openness, and population growth are among the main influencing factors of ERE. The findings revealed that temporary short-term policies have noticeable impact on the regional ERE, and "matching effect" between the ERE and regional economic development does not present.