The invention provides an adjustable combined-effect dedusting device used for a pulse spraying dust cleaner. The device includes a spray pipe and multiple groups of spray nozzles communicated with the spray pipe; the spray nozzles are arranged in the length direction of the spray pipe at intervals, each spray nozzle is composed of a circular tube and a multi-segment spray nozzle passage running through the circular tube axially, and each multi-segment spray nozzle passage includes the stable segment, the shrinkage segment and the expansion segment which are sequentially connected with one another in the length direction; each stable segment is cylindrical, each shrinkage segment is in an inversely circular truncated cone shape, and each expansion segment is in a circular truncated cone shape; the connected area between each shrinkage segment and the corresponding expansion segment is a neck part of the corresponding spray nozzle, and an adjusting assembly capable of adjusting the areaof the neck part of the corresponding spray nozzle is arranged on each stable segment. Through combination and reconstruction of the spray nozzles which are shrunk at first and then expanded and adjusting core rods, the areas of the neck parts of the spray nozzles are adjusted, spraying performance under different working load states and different spraying work conditions is obtained, and efficient dedusting requirements are met. The device can be widely applicable to spraying dedusting by bag-type dust cleaners, filtering drum type dust cleaners and other equipment adopting tubular and cylindrical filtering materials for dedusting.