A trampoline support frame comprises transversal and longitudinal branch pipes. The transversal ones are connected to form an annular frame. Each longitudinal one is provided with a fitting portion and two reinforcing portions integrally extended from the fitting portion to corresponding two side surfaces of the transversal one and then fixed to the transversal one by welding. The two reinforcing portions of each longitudinal one are extended from and integrally formed with the fitting portion, such that each transversal one is fixed to the two reinforcing portions by welding directly after the transversal one is placed between the two reinforcing portions without precision alignment, whereby the manufacturing process for the trampoline support frame is simplified, and manufacturing energy consumption is reduced to meet requirements for environment protection. Assembling strength between two opposite outer side surfaces of each transversal one and each longitudinal one is strengthened by the two reinforcing portions.