In this paper, a new queuing model G (General arriving) /G (General Service) /1 (One Server)/ S (Number of limited buffers ) / FCFS (First Come, First Served) is proposed for integrated service with limited buffers in loop LAN. The model is built through reconstructed probability space in discrete time. According to the imbedded Markov chain theory and the generating function, a mathematical analysis and computer simulation have been developed in this paper. The mean queue length the delay time of packets of the system and the probability of packet loss are explicitly obtained. The results of computer simulation show their concordance with the theoretical analysis.