Air duct system, combustion device and gas stove

The utility model relates to the technical field of kitchen equipment, in particular to an air duct system, a combustion device and a gas stove. The air duct system comprises a fan, a first shell and a second shell, the first shell and the second shell are buckled with each other, and an air duct cavity is defined by the first shell and the second shell. The draught fan is connected with the second shell and used for driving airflow to flow to the fire cover assembly from the air channel cavity so as to provide secondary air supply for the fire cover assembly. According to the air duct system of the combustion device, the air duct system with the air duct cavity is arranged, so that the air duct cavity can provide a buffering and pressure reducing space for air flow with high flow speed and high air pressure, and the air flow can be uniformly distributed in the air duct cavity firstly and can enter the fire cover assembly more stably; therefore, stable supplementary airflow can be provided for the combustion