Abstract: Regarding the lack of consideration about spatiality and fuzziness in the traditional methods in drawing out the dam safety monitoring index, this paper decreases dimensions of displacement sequence at different heights in a dam by projection pursuit (PP) method to generate the projection displacement value and the displacement weight, and then takes the forward and inverse cloud model to draw out the safety monitoring comprehensive index for dam displacement based on the calculated weighted displacement value. Taking Mianhuatan RCC gravity dam as an example, the safety monitoring comprehensive index of horizontal displacement for No.4 dam section is worked out by PP model and the cloud model. This paper analyses the correlations between the weighted displacement of the dam body and environmental variables, and for a super scalar value of displacement, it makes comparison with the results of the confidence interval method to demonstrate the rationality and feasibility of the projection pursuit method.