Aimed at the problems of the buffer lifting hydraulic cylinder of the spud of cutter suction dredger,such as the large starting pressure, the large impact force when the cylinder falls back, the poor working stability and reliability during operation and the short service life, the whole structure of the hydraulic cylinder was redesigned. At the bottom of the cylinder block, the doubleinlet and singleoutlet oil circuit was used, and the oneway valve was used to control the oil circuit, so the starting pressure was small. At the bottom of the piston rod, a buffer device combined with a buffer spring and a throttle hole was used to reduce the speed and impact force when the piston rod falls back. The result shows that the stability and service life of the improved buffer lifting hydraulic cylinder are greatly improved.