The internal force state of a curved bridge is quite different from that of a straight bridge of the same span. The straight bridge is simple to bear force, while the curved bridge is greatly affected by the eccentricity of the dead load, live load and bending-torsion coupling, and the modeling and calculation are relatively complex. Therefore, in order to simplify the calculation, bridge engineers often use the straight bridge model instead of the curved bridge model. However, how much difference there is between the above simplified model and the actual force condition of the bridge remains to be studied. Based on the actual project, this paper used Midas Civil to establish a plane bar beam unit model of the same size and span, a space model of the straight-replacing curved beam grid method, and a curved beam model of the beam grid method, and configured the same steel bars and steel strands. From the actual comparison results, the experience is summarized, and the differences in the internal force results of the three models are as follows: (1) Under the most unfavorable load combination, the mid-span deflection value of the single beam straight model is greater than the mid-span deflection value of the beam grid method straight model, of which the former is 6% greater than the latter; the mid-span deflection value of the beam grid method curve model is greater than the mid-span deflection value of the single beam model, of which the former is 3% greater than the latter. (2) The support reaction values of the beam grid method space model and the beam grid method curved beam model are greater than the support reaction values of the single beam model, and the outer side of the curve is greater than the inner side of the curve. (3) The maximum mid-span bending moment value of the beam grid method space model and the beam grid method curved beam model is 1/4 larger than that of the single beam model, and the absolute value of the minimum bending moment of the support point is also the same. This study can draw the following conclusions for future design reference: The bending moment borne by the curved beam is greater than that of the straight beam, especially the beam outside the curve. Therefore, when designing a curved bridge, more prestressed steel strands should be configured and different numbers of steel strands should be configured for the main beams at different positions.