The invention discloses a structural diaphragm for low-pressure blasting. An I-shaped notch groove structure is adopted, the structural diaphragm can crack along an I-shaped notch after blasting is accomplished, and notch-free sections are arranged on the left side and the right side, and are used for connection. The structural diaphragm is completely attached to the inner wall of a holder after blasting is accomplished, and cannot fly off or fall off, the requirement that the normal-temperature blasting pressure difference ranges from 0.20MPa to 0.27MPa is met, the problem that a traditional single-hinge type notch diaphragm cannot achieve low-pressure blasting, and can be easily blown off after blasting is accomplished is solved, and safety and reliability of rocket launching are improved.