Effective combination and carry-loading together between steel and concrete play important roles for the steel-concrete composite structure. The steel-concrete composite joint decides the constructing safety and life-cycle performance as the key member for the steel-concrete composite arch bridge. The stress distribution in the steel-concrete composite joint was studied by model test under pressure-bending load. And the stress transfer was probed in the steel box, composite joint and reinforced concrete box. The result shows that the steel and reinforced concrete boxes are under elastic compression in the steel-concrete composite joint. The bearing plate can effectively reduce the stress in concrete and steel boxes. This plate and stiffener can smoothly transfer and scatter the stress from steel box to concrete box. The failure mode is concrete cracking near the interface between steel box and concrete box under large eccentric compression.