This paper analyses the multi-product manufacturing system with setup time, buffer breakdown and arbitrary processing time. The discrete-time Markov chain model is established by constructing the state vector of the system. In order to calculate the system state transition matrix, the system state is divided into four kinds of situation to be discussed according to the production process of the multi-product manufacturing system. On the basis of the system steady-state probability, the calculation procedure of system throughput is further obtained. Based on the proposed model, we give a detailed solution to the multi-product manufacturing system with symmetric parameters which can produce two kinds of products, and provide the calculation formula of system throughput. Through Matlab experiments, the impacts of system parameters on system throughput are analysed and summarized, such as the failure-free rate of buffer, the product arriving rate, the setup time, the processing rate and its coefficient of variation.