This article empirically tests competing positions about the influence of local autonomy on environmental regulation implementation. Environmental regulation authority is currently distributed between Central government and local governments. Local autonomy influences intergovernmental relationship in implementing regulatory policy by enhancing local autonomous power. This study also tests three other important theories(wealth. financial capability and interest group) in an attempt to explain enforcement efforts of local governments along the Han River. The analysis discloses that enforcement effort of overall local governments diminished since local autonomy in 1995, while Central government engaged in more stringent enforcement. The TSCSREG(time-series cross sectional regression) on 33 local governments along the Han River also shows that local autonomy is associated with lax enforcement. In explaining variations in regulation implementation, the findings present that financial capability of local governments is positively related only to monitoring efforts and greater wealth leads to greater enforcement vigor. Another important finding is that local regulatory efforts are significantly influenced by regulated industries supporting capture theory, while environmental groups have no influence. Based upon data analysis it is suggested that Central government needs to provide selective incentives such as partial preemption or cross subsidies to induce local enforcement efforts. In particular, financial programs should be parallelled with monitoring enforcement. performance of local governments along the Han River in order to improve water quality of Paldang-Reservoir.