Based on telephone surveys and in-depth interviews with small and medium-sized water-sensitive enterprises in Tianjin City, we studied the key factors that influence these enterprises’ willingness to participate in PES, the methods of compensation, and other related problems. The results show that these enterprises prefer capital compensation to the water source area, and they look forward to political support from the government. The enterprises’ scales and subject positions, as well as the completeness of legislation affect their willingness to participate to different extents. Simultaneously, their knowledge of the PES mechanism is quite limited, which weakens their willingness significantly. Related authorities should strengthen the promotion of the PES mechanism, improve the laws and regulations regarding compensation methods and stimulation mechanisms, and formulate compensation standards based on scientific calculation as soon as possible.