To investigate the validity of Chinese law enforcement from the public's perspective, this research applies the theory of planned behavior, and introduces law as a moderator variable to explore the determinants of public's environmental behaviors. Results from an empirical study of China indicate that perceived behavioral control, subjective norms, inward attitude, and outward attitude all have positive impacts on environmental intentions and indirectly affect the citizens' environmental behavior and activists' environmental behavior. Meanwhile, legal cognition positively moderates the relationship between environmental intentions and behaviors. As the level of the public's legal awareness increases, the direct effect of these two types of environmental intentions on environmental behaviors respectively continues to increase. Based on the findings, some constructive implications are provided to the governments and legislators to strengthen public participation in environmental protection.