Abstract: The downlink outage probability of the distributed MIMO systems over a composite channel was discussed. Firstly, a composite fading channel was established by integrating Nakagami-m fading, path loss, and lognormal shadowing. According to the distributed MIMO system with a center-located base station (BS), a quasi-uniform mobile station (MS) distribution model was proposed, which is more suitable for a real communication environment. Next, an approximate analytical expression of average downlink outage probability of the system with arbitrary MS distribution was derived through using mathematical methods such as moment generating function, Gauss-Hermite integral, composite Simpson’s rule and so on. Finally, by taking the proposed MS distribution model into account, the derived closed-form outage probability expression and the MS distribution were proved to be correct and reasonable by computer simulation results.