An elevation-adjustable support structure includes a connecting member, a bottom hinge structure, which comprises two bottom brackets, and a shaft fastened to the bottom brackets and pivoted to the bottom end of the connecting member for allowing the connecting member to be turned about the shaft between the two bottom brackets, a top hinge structure, which comprises two top brackets and two shafts respectively fastened to the top brackets and pivoted to the top end of the connecting member for allowing the connecting member to be turned about the shafts between the two top brackets; and two linking mechanisms each having a top wheel and a bottom wheel respectively coupled between the top end of the connecting member and the top brackets and the bottom end of the connecting member and the bottom brackets and a flexible belt member coupled between the top wheel and the bottom wheel for maintaining the angle of inclination of the top brackets upon a rotary motion of the connecting member relative to the top hinge structure and the bottom hinge structure.