This article uses the concept of legislative institutionlization to analyze the durability, boundares, and internal complexity of the National People's Congress. Under Mao Zedon's rein, the NPC was low in durability. The legislature met irregularly and neither the selection of the deputies nor the terms of the deputies were institutionalized. Since the 1980s, the durability of the NPC has greatly improved. Since the 7th NPC, the overlapping of personnel between the NPCSC leadership and the CCP's Central Political-Legal Commission has been disconnected. Nevertheless, the high turnover rate of the NPCSC leadership and its members suggests that the legislature is still not well bounded. However, the trend towards professionalism is beyond doubt. Since the 1980s the legislative committees have gained strength both in size and in power. Most of the laws passed by the NPCSC are being drafted by the committees. The introduction of the hearing system is a significant step towards increasing the quality of legislation. Addition staff members and reinvigoration of subsidiary organizations are also indications of heightened internal complexity.