The invention discloses a garden waste incineration boiler. The garden waste incineration boiler comprises a hearth, a steel frame, a fire grate, a feeding system, a horizontal flue and a tail flue. The back of the hearth is sequentially provided with the horizontal flue and the tail flue which are arranged to be in an n shape. An ash hopper and a backdraft pipe are arranged on the lower portion of the horizontal flue. The fire grate is a reverse chain fire grate. Baffles are arranged on the upper portion of the last row of tube bundles of a middle-temperature superheater, and clearances are reserved among the baffles. The feeding system is arranged in front of the hearth and comprises a garden waste bin, a standby stock bin, conveying devices, air supplying devices and a feeding hopper. The feeding system can be uniformly arranged to be in a multi-line parallel mode according to the width of the fire grate. The feeding hopper is divided into an upper layer and a lower layer, the upper layer is a garden waste hopper body, the lower layer is a standby fuel hopper body, and the independent air supplying devices are arranged on the garden waste hopper body and the standby fuel hopper body correspondingly. According to the garden waste incineration boiler, garden waste can be efficiently processed, and the feeding system can be flexibly and conveniently adjusted according to the change conditions of the garden waste so that continuous operation of the boiler can be ensured.