The invention provides a piston-driven straight-through type pressure and flow regulating valve. The piston-driven straight-through type pressure and flow regulating valve comprises a main valve and apilot valve connected with the main valve, an outer shell and an inner shell of a valve body of the main valve are coaxially arranged, a valve cavity is formed between the outer shell and the inner shell, and a driving device is installed in the inner shell in a sliding mode in the axial direction; an end cover with a spherical structure is arranged on the side, facing a first port, of the innershell; and the inner walls of the two ends of the shell are each of an arc-shaped structure, the inner diameter of each arc-shaped structure is gradually reduced from inside to outside, long grooves are formed in the axial direction of a pup joint, and the outlet side pressure of the valve body is adjusted through the length of the long grooves in a pressure reduction opening-closing piece extending into the valve cavity. A pressure reducing valve provided by the straight-through type pressure and flow regulating valve has high distribution capacity, water flow energy counteracts each other atthe arc-shaped structure at the outlet of the valve body, cavitation and vibration can be effectively avoided, and due to the fact that the pressure reducing opening and closing piece is subjected tothe effect of control pressure of the guide valve, the valve has a pressure regulating function, water head loss is very small during opening and closing, and resistance is small during complete opening; and meanwhile, the valve is closed tightly and is good in sealing performance.