The invention discloses a three-layer laying hen cage capable of realizing automatic feeding, egg-picking and manure-cleaning. The three-layer laying hen cage is characterized in that a transmission adjusting mechanism, an egg picking trough assembly, a long feed trough assembly, an automatic manure-cleaning assembly, trapezoid racks and a carriage are mounted between an egg picking box assembly and a material feeding and mixing assembly; the hen cage has three layers, and multiple hens are placed on each layer; long feed troughs, egg picking belts and egg feeding belts are arranged at the front of the hen cage; a manure belt is arranged at the bottom of each layer of the hen cage; a manure scraping plate is arranged on each manure belt for scraping hen droppings; an egg unloading plate and egg supporting hooks are arranged on each egg feeding belt; material guiders and adjusting screws for adjustment of feeding and discharging are arranged on feed hoppers for feeding. According to the three-layer laying hen cage, the automatic feeding, automatic water feeding, automatic egg picking and automatic manure cleaning can be realized, the design is simple, various functions are achieved, a great number of hens are raised, materials are reduced, time and labor are saved, the benefit is great, the cost is low, and raised hens grow faster and lay plenty of eggs.