Hydraulic cylinder with built-in stroke valve and folding header of silage maize harvester

The hydraulic cylinder with the built-in stroke valve comprises a hydraulic cylinder body and the stroke valve, a piston assembly is arranged on a cylinder body inner cavity of the hydraulic cylinder body, and the piston assembly slides in a reciprocating mode in the length direction of the cylinder body inner cavity; the stroke valve comprises a valve body, an end cover and a valve element rod. The valve body is arranged at the bottom of the hydraulic cylinder body, a first oil cavity and a second oil cavity are formed in the valve body, a sealing step is formed at the joint of the first oil cavity and the second oil cavity, an oil inlet communicated with the first oil cavity and an oil outlet communicated with the second oil cavity are formed in the valve body, and a guide hole is further formed in the valve body; a containing cavity is formed in the end cover, and an elastic piece is arranged in the containing cavity; an oil passing hole used for communicating the inner cavity of the cylinder body with the