A regression model of dam crest’s horizontal displacement was established using the monitoring data of horizontal displacement (along the river flow direction) and temperature of the Three Gorges Dam. The model prediction result is very good with highly significant regression coefficients. Through quantitative analysis, it’s found that dam crest’s horizontal displacement in the flow direction is mainly affected by reservoir water level, making up 80%-90% of the entire displacement; and temperature of the dam body is the second largest influencing factor, accounting for 10%-18%. Years of displacement monitoring data shows that the deformation of the dam is normal within the design range, in a good linear relationship with hydraulic load. The relation between temperature and dam structure conforms well with physical mechanics laws. Displacement caused by ageing is very small, which reveals that the dam body and foundation are quite stable, with no irreversible deformation. It’s also found that taking the temperature at dam’s typical parts as the temperature factor is feasible and convenient. The research provides reference for following monitoring management and concrete structure design.