It is essential to avoid or reduce construction errors when field connecting curved steel girders together with diaphragms. Construction errors usually change the mechanical system, create unexpected internal forces and residual stresses in steel girders or diaphragms, which cause construction difficulty of follow-up work and create safety issues. In this article, as a case in point, two inner supports of a curved two- steel girder pedestrian bridge were uplifted when two steel girders being tied together by the diaphragms. To continue upper concrete deck work, a temporarily added dead load at both ends of girder was applied. Through field investigation and based on mechanical reasoning, we detected the main cause of the uplift. Moreover, we built a finite element model to simulate the procedure of construction step by step and stresses of every step were obtained. In the meantime, displacements of the supports were monitored by laser measurement system while the added dead load was released. When the whole bridge construction was completed, a field loading test was taken, displacements and strains were measured. Compared the calculation result with the test data, we drew a conclusion that the installation error produced very low residual stress, and there is no effect to the structural safety under the full design load.