The invention relates to the technical field of electric light source lighting, and particularly relates to a dual-full-bridge injection phase-locking power synthesis neon lamp. Two RC oscillators are both connected to a resistor R11 and a capacitor C14 and oscillate synchronously; a self-oscillation chip 4, an output power transformer T1 of a full-bridge inverter A, a self-oscillation chip 6 and an output power transformer T2 of a full-bridge inverter B are fed into an adding coupler in opposite phases; synthesized power, booster voltage and rectified current are fed into a lamp tube; reference crystal oscillator signals are injected into the RC oscillators of the two self-oscillation chips 4, 6 to lock the phase; and large-power lighting is acquired, thereby avoiding too high temperature rise of devices, changes in oscillation frequency, unbalance of the power and reduction of the lamplight; and lamp tube abnormal current detector signals are connected to SD ends of the oscillators of the two self-oscillation chips, thereby controlling quick stop of the oscillation so as to turn off a power tube of the full-bridge inverter. The dual-full-bridge injection phase-locking power synthesis neon lamp is applied to commercial decoration large-power neon lamp advertizing lighting.