The invention relates to a device and a method for controlling the diffusion of a gas collecting pipe. The device comprises a burner, a diffusion pipe, an igniter cabinet, a control cabinet, a diffusion valve, a diffusion valve executing mechanism, a fire collection valve, a fire extinguishing valve and a pressure transmitter, wherein the burner is positioned at the upper part of the diffusion pipe, the igniter cabinet is connected with the burning torch on the burner through a cable, the fire collection valve is connected with the fire collection pipe of the burner, and the fire extinguishing valve is connected with the fire extinguishing pipe of the burner; the diffusion valve is positioned at the joint of the diffusion pipe and the gas collecting pipe and connected with the diffusion valve executing mechanism, and the pressure transmitter is arranged on the gas collecting pipe at the inlet of the diffusion pipe; and the motion of the diffusion valve executing mechanism of the gas collecting pipe is controlled through the continuous monitoring of the pressure of the gas collecting pipe, the fluctuation of the pressure is maintained within a reliable range, the sequential motions of the associated ignition device, the steam fire collection and smoke abatement valve and the steam fire extinguishing valve are synchronously controlled to achieve the optimal scheme. The invention has the advantages of rapid response, safety and reliability, good burning effect and environmental protection.