The reasonable selection of blackstart scheme is significant to the fast restoration of power systems however most previous studies are based on complete evaluation information without consideration for cases with incomplete evaluation information. Under this background, the Affinity Propagation (AP) algorithm and Slope One method are adopted to assess blackstart schemes with incomplete evaluation information in this paper. Firstly, the Affinity Propagation algorithm is utilized to cluster the blackstart schemes to generate similar sets of schemes. Then, the Slope One algorithm is employed to predict the absent values according to the evaluation value of the blackstart schemes in the same cluster. Finally, the standard deviation and the TOPSIS methods are applied to rank the schemes. The relative data of Guangdong power system are selected to evaluate the performance of the proposed method. Four existing blackstart decision making methods with complete information are compared with the proposed method. The result shows that the proposed method solves the problem of incomplete evaluation information well.