This decision model is developed for evaluating and selecting a proper formwork system in building construction. The hierarchical structure of the formwork system evaluation model is constructed by five aspects: quality, schedule, cost, safety and constructability. Twelve evaluation indices are selected and established in the hierarchical structure. The analytic Hierarchy Process (AHP), Fuzzy Multiple Attribute Decision Making (FMADM) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods are combined to evaluate and rank the alternatives of formwork systems. The application of the decision model provides an objective guide for decision-makers in the process of a building construction project.