Explosive logic network is a key technology to the aimable warhead, and gap null gate is a basic logic element of explosive logic network. It is necessary to realize the function of the gap null gate. A transmitting-explosive based on RDX was developed, and a gap null gate with the transmitting-explosive was validated experimentally. Formulations of the transmitting-explosive and the gap distance suitable for the gate were concluded. The detonation velocity of the selected transmitting-explosive was measured, and a gap null gate in small scale was designed. The gap null gate will proved reference for designing the explosive logic network.