Abstract: Aiming at the problem that the conventional method is difficult to calculate the steady state availability for complex repairable equipment group, a method of constructing multiple continuous time Markov chain (CTMC) is proposed to solve its steady state availability. With consideration of the features of the use and maintenance- of the equipment group, three parameters, which are the number of equipment, spare parts inventory and expected backorder respectively, are proposed to represent the inventory state of components. Then, the CTMC for each component is established, forming a CTMC family to analyze the steady state availability of the equipment group. Based on the state transition relations and the transfer rate matrix of each component, the algorithms for each component expected backorder and the steady state availability of the equipment group are given. Finally, a numerical analysis case is constructed, which shows that the result of the CTMC family model proposed is closer to the simulation results than the multiechelon technique for recoverable item control model, verifying the validity of the proposed model and algorithm.