In the practice of prosecution’s power of legal supervision，the exercising subject has not been separated from other exercising subjects of power The confusion of exercising subjects of different power has generated a lot of negative consequences，which bring about the criticism and doubt of the prosecution’s power operation of legal supervision In the future，the department of legal supervision within the prosecution would be set up independently，which exercises the power of legal supervision separately The independence of legal supervision subject has the legal basis，its realization needs three “relative separation”