Pakistan-China Digital Seismological Network is a project which is China aid for Pakistan . This article introduces the Communication System and Network System in the PCDSN , especially introduce the satellite communication system which used in Pakistan , including user required , carrier plan , link budget and configuration. This article also introduce the Microwave communication system which used in communication in short way and the method of the remote maintenance. The last this article briefly introduce the design of network in PCDSN.