According to the ubiquitous uncertainty of resource availability, a multi-objective military mission planning model with uncertain resource availability is proposed based on reasonable hypotheses. A proactive schedule method based on resource buffer was designed according to the special features and particularity of the model. In the method, the resource buffer was added into the project during the task-platform allocation in order to minimize the disadvantage of resource uncertainty; the multi-objective evolutionary algorithm NSGA-Ⅱ was adopted to calculate the Pareto Front of the problem. Finally, an example was illustrated to show the feasibility and practicability of the proposed model and method.