Steel-concrete composite beams are widely used in bridge structures and fatigue damage caused by vehicle loads will accumulate gradually, which is adverse to the structure safety. To study the influence of fatigue damage on the mechanical performance of steel-concrete composite beams, monotonic static tests were conducted on seven composite beams, including five composite beams previously suffered 1,000,000 cycles of constant amplitude fatigue loading. Experimental results indicated that fatigue damage due to 1,000,000 cycles of fatigue loading caused the reduction of ultimate deformability of the composite beams. However, the ductility coefficients were still greater than 4.6 and the final failure patterns belonged to flexible failures. Fatigue loading led to the strengthening effect of steel material and the yielding loads of the composite beams improved correspondingly. The ultimate bearing capacities of the composite beams with partial shear connection generally reduced and the maximum drop reached 7.3% of the initial ultimate bearing capacity. Using studs with 13mm or 16mm in diameter has no significant effect on the bearing capacity of the composite beams when they possess the same shear connection degree.