The invention discloses an enrichment valve controlled by a trigger signal to start. The enrichment valve controlled by a trigger signal to start comprises a first circuit, a second circuit, a third circuit, a capacitor, a control module, a silicon-controlled rectifier and an enrichment valve and is characterized in that the positive wire of the enrichment valve is in parallel connected with the first circuit by a terminal and a positive power supply end of the control module; the negative wire of the enrichment valve is in parallel connected with the collector electrode of the silicon-controlled rectifier, the discharge electrode of the silicon-controlled rectifier, the negative electrode of the capacitor, the power supply negative end of the control module and the second circuit by the terminal; the base electrode of the silicon controlled is connected with the signal output end of the control module; and the signal input end of the control module and the positive electrode end of the capacitor are connected with the third circuit. The engine works, and the rotation speed exceeds 800 revolutions per minute, the signal generated by the trigger is filtered by the capacitor to enter the control module; after the control module senses that the engine works, forward voltage is transmitted to the base electrode of the silicon-controlled rectifier, then the silicon-controlled rectifier conducts, and the enrichment valve starts to work, thereby achieving synchronously switching on and off with the engine by the trigger signal.