The main bridge of Shandong Gaoshang Yellow River Bridge adopts a structure system of (190 + 260 + 260 + 190)m four spans continuous CFST rigid-frame tied arch bridge. Three sets of tied rods are set to balance the horizontal thrust of the arch seat. The form of a stepped steel box-concrete composite arch seat that filled concrete and enveloped steel plates is adopted. The numerical analysis method combining the beam element and solid element calculation model was adopted to analyze the force performance of the arch seat. Comparing the superiority of the steel box-concrete composite arch seat design over the same size concrete arch seat. Results show that, under the same loading conditions, the force of each component of the steel box-concrete composite arch seat meets the requirements, while tensile stress at the rib grooves and step corners of the arch seat exceeds the standard value in a wide range, and the force performance cannot meet the requirements of normal use. The width has to be extended by 38% of the original dimensional width, the thickness by 14% of the original dimensional thickness, and the overall volume of concrete has to be increased by approximately 70%. The steel box-concrete composite arch seat is a reasonable form with substantial improvement in economy and construction convenience compared to the concrete arch seat.