The invention discloses an energy-saving exhaust pipe featuring changeable pressure, comprising a sleeve; the sleeve is provided with an air inlet and an air outlet respectively; the rear end of the sleeve and the margin of the air outlet are respectively provided with a cover plate and a baffle plate; the air inlet, the air outlet, the cover plate and the baffle plate form a closed chamber in the sleeve; a mounting pad is fixed in the closed chamber positioned at the back of the sleeve; a piston rod penetrates through the cover plate, the mounting pad and the baffle plate; the front end of the piston rod is provided with a piston sheet; the part of the outer wall of the piston sheet, which is in the closed chamber, is sheathed with a supporting plate corresponding to the size of the closed chamber; the supporting plate is provided with a spilehole; the outer wall of the piston rod is sheathed with a spring between the supporting plate and the mounting pad; an adjusting bolt is arranged at the rear end of the piston rod; a buffer spring on the outer wall of the piston rod is arranged at the front end of the adjusting bolt. The energy-saving exhaust pipe has the advantages of simple structure, low cost, unnecessary control by control systems, long service, convenient installation and environmental protection and can achieve the aims of improving drive, hoisting power and reducing exhaust and mechanical noises.