A trampoline frame structure includes a side frame (1) and a number of support legs (2). The side frame (1) includes a number of side frame tube sections (10), where each side frame tube section (10) and two support legs (2) are formed integrally into an upside-down U shaped side frame member (3). Each pair of adjacent side frame members (3) are connected together by fasteners (2, 4) that connect adjacent support legs (2) of the two side frame members (3), and the multiple side frame member (3) collectively form a closed shape in the top view. The entire trampoline frame can be formed without welding, which simplifies the manufacturing process and accomplishes a trampoline frame having high strength and low manufacturing cost.