In prestressed components, the prestress loss of ultra-long spatial curved beams is usually large, and the existence of construction errors will increase the prestress loss and reduce the effective prestress, which usually has an adverse effect on the structure. Therefore, in the analysis of prestressed structures, it is necessary to consider the influence of construction errors, measure the prestress loss of ultra-long spatial curved beams, and revise the relevant coefficients for calculating prestress loss to examine the impact of actual prestress loss on the bridge structure. This paper takes the bottom plate through-length beam of a continuous beam bridge as an example, determines the value of the friction coefficient that has the greatest impact on prestress loss through field measurement of steel strand stress and theoretical analysis, and then revises the structural finite element model based on this to study the impact of prestress loss caused by construction errors on the bridge structure.