In order to clarify the importance and difficulty of the bridge construction in the lake-crossing area and to better manage the construction site, taking the bridge construction in the lake-crossing area of a city as the engineering background, 26 influencing factors are selected to construct the risk assessment system of the project. Six key influencing factors are extracted by principal component analysis, and six indexes are selected as evaluation indexes: bench shift accumulation Q, pile side friction standard value qik, number of rectification points N, clearance height H, rainfall days T and average score G of safety training. Cloud model and principal component analysis are used to comprehensively evaluate the construction risk of bridges in the lake area. The results show that:①The principal component analysis method extracts six key influencing factors of the project and defines the key protection areas of the on-site construction operation;②Through the comprehensive evaluation, the bridge construction risk grade in this area belongs to the second grade and is in the acceptable risk range, so it is necessary to implement targeted preventive measures to the key protection areas to ensure the construction safety.