Abstract: In a network system,overflow or overwrite of message buffer will cause missing of messages.For a timed token network,message transmission time and the message buffering space allocation in a node are very important issues on network real time capability.This paper analyses the message buffering mechanism,describes the relationship of message buffering space and message transmission bandwidth allocation,and proposes a space determination method of message buffer for LTPB network.The maximum space redundancy avoiding buffer overflow for send and receive buffers has been derived.It is found that the space of send and receive buffers is equal to the message size under condition that the message gap time is greater than message latency and node response time.