Abstract: Performance,cost and reliability are three important parameters for a system.Performance and cost of the Fifth Generation Computer (FGC) are widely studied in many papers.This paper stresses on the reliability design of the FGC.The conflict in the reliability with the complexity of FGC system constructed by VLSI circuits is discussed; and some solutions to the conflict are proposed.The conclusion is that the FGC must be a highly reliable fault-tolerant system.At last,a brief introduction is given about the relative work in our university.