The mission dependability of repairable systems not only depends on mission reliability and capacity of the system, but also the maintenance capacity during the whole mission. The probability of mission successful completion is one of the important performance measures. For the complex mission that has many submissions of kinds, its success probability is associated with the ready and execution duration, maintenance conditions in the working field and success requirements of each sub-mission. Maintenance conditions in the sub-mission working field mainly include replacement and repair of the failed components. According to these different maintenance conditions, we classify all sub-mission into three classes. By analyzing the state transition during the ready period and execution period of each sub-mission, this paper presents a dependability model to evaluate the probability of mixed multi-mission success of repairable systems considering maintenance capacity. A simple example is provided to show the application of the model.