In last ten years, academic circle and judicial circle are both interested in public interest litigation. Specially, a large number of researches present western system of administrative public interest litigation. However, China's procuratorates are judicial authorities, and their function is legal supervision. In China's legal context, the identity of public interest agent of procuratorates is incompatible with the spirit of the constitution. It will initiate indiscriminate lawsuits and then mutation of lawsuits, and give rise to a set of negative influences. However, all of these problems are not procuratorates' intention. That procuratorates cannot obtain the power of censoring abstract administrative act illustrates the weakness of legal supervision. So, we ought to improve the system of legal supervision and its framework in the background of judicial reform.