The block set mechanism was used to analyze the characters of pull-out capacity and failure surface of anchor plates. An application to upper bound analysis of vertically loaded strip anchors on horizontal ground surface is given first to illustrate the utility and effectiveness of the proposed method，and include detailed comparisons with model test results of Das[1] and Rowe[2]. Then analyses of anchor plates were given with emphasis on consideration of sloped ground. Comparisons between theoretical predictions of block set mechanism and model test results of Khing et al[3] and Rao and Prasad[4] are presented. The results show that the steel rod which adopted in model test as a loading device has a significant effect on pull-out capacity of anchor plates. So the Trapdoor model should be given priority in the model test of anchor plate which the sloped ground was taken into consideration.