In the past three years, the author has participated in several projects involved in Intelligent Network (IN). In 1997, we started our research on the project “The Integration of IN and B-ISDN” supported by National Science Foundation. Since 1999, the author has engaged in the project “the Next Generation IN Based Service Platform Interworking with IP Networks” supported by the National 863 Project. While working on the project, the author made a deep research on the architecture and the key technology of the next generation IN defined by ITU-T IN CS3 and CS4. In the following parts. 1. I conclude the research work and the innovation in my dissertation. The early research on the interworking of IN and Internet, despite the shortage of materials, the interworking architecture by means of IAF is analyzed. Some key techniques like triggering intelligent service and reporting dynamic IP address are solved. Some new SIBs and INAPs are added, and the dial-up software of users is enhanced, too. The incoming call notification service is designed. What we have done paves the way for the future research. 2. The gateway based architecture for the interworking of IN and Internet is described. Considering the research results from ITU, PINT work group and TIPHON work group, we emphasize that the interworking scenario through MG,SCG and C/BG is promising. Based on the CIN software developed by ourselves, we provide the scenario to enhance the function entities and signaling protocol. We address the function of entities and the interaction of signaling with an example like ICW service. 3. With the introduction of mobile agent technology, the author proposes the distributed IN which can be integrated with IP networks. According to the drawbacks of the centralized IN, we address the architecture and conceptual model of distributed IN to support advanced service in IP Telephony. We try to illustrate the role and relationship between function entities. We also present a smooth evolution scenario from todays networks. 4. A novel service control software based on mobile agent technology is proposed. With the adiquately understanding of CIN 02 SCP, we present the OO based framework of MA-SCP. And we explore how our new SCP works. We prove that our solution can work efficiently by a service called VPN in IP Telephony. 5. The concept, architecture and related research of active networks are introduced. We take the ticket order service as an example, give the simulation results and prove that active networks can improve the performance of distributed applications. We also compare active networks with mobile agent based IN. We highlight that the two techniques can complement each other and borrow lessons from the other one. 6. The architecture of Broadband IN is discussed. From the angles of architecture, access mode and software structure, a novel B-IP that can support multimedia services such as VoD and B-VPN is given. Moreover, B-IP is introduced into VoD service. To improve the performance of VoD, we present a novel replacement algorithm with the multi-layer decision with multi-factors.