Abstract: The second-joint video terminal system for Dong-Huang Oil Pipeline has been developed in order to improve the line's field operating supervisory, field operating status, display of Chinese characters and screen copying. This system, being two VAX Ⅰ hosts designed, respectively connects with communication transfer switch of S/3 system via RS-232 port and with communication concentrated module through modem. The communication network server can achieve the function of all files-in-share. For data transmission, the system's host uses the protocol of package & unpackage, and its best communication band rate is defined as 2 400 bit/s. The field operation results show that the two VAX Ⅱ hosts can be switched to another automatically in "hot condition" after the new system has been put into operation, and all data in them can be refreshed at the same time. It brings about the following functions; Chinese display, monochrome and/or color screen copying, alarm-pieces display and eitht-trend curves display on one screen.