The present invention provides a catalyst unloading device and method for a synthesis reactor, wherein a negative pressure is formed by a fan, and a
solid-
gas mixing chamber, a separator and a
dust collector are sequentially arranged along the
airflow direction on the air path between the synthesis reactor and the air inlet of the fan; the
solid-
gas mixing chamber is a shell structure of an indoor cavity, and a tangential inlet of the separator is introduced through a
discharge pipe in the middle of the front bottom end along the
airflow direction in the cavity, and an adjusting air duct with an adjusting valve is formed in the middle of the rear bottom end, and the
air volume can be adjusted by adjusting the opening of the adjusting valve, and the
solid-
gas mixing chamber leads out a plurality of particle suction pipes connected to the cavity and independent of each other from the
peripheral wall, and each particle suction
pipe is inserted into the catalyst
bed in the tube from the top of the corresponding tube array and can move up and down in the tube array; the outlet of the separator is connected to the inlet of the
dust collector through the air duct, and the outlet of the
dust collector is connected to the air inlet of the fan through the air duct. The present invention is easy to implement and maintain, saves manpower and
operation time, and reduces costs and improves efficiency.