The invention discloses a method for manufacturing a titanium alloy thick-wall pressure-resistant cylinder body. The method comprises the following steps of: 1, cogging and forging a cast ingot serving as a raw material to form a bar blank; 2, upsetting and drawing the bar blank repeatedly for forging to form a bar; 3, performing annealing treatment or solid solution treatment on the bar to eliminate residual stress of the bar; 4, drilling and boring deep holes of the bar on deep hole drilling and boring machine equipment in an internal chip removal mode, so that a cylinder body blank of which the length is the same as that of the bar is machined; and 5, finely boring the internal surface of the cylinder body blank and turning the outer surface of the cylinder body blank to obtain a thick-wall cylinder body of which the wall thickness is more than or equal to 15 millimeters or finely boring the internal surface of the cylinder body blank and turning the outer surface of the cylinder body blank, and aging to obtain thick-wall cylinder body of which the wall thickness is more than or equal to 15 millimeters. The thick-wall cylinder body is manufactured integrally by the method without being welded, so the anti-stress corrosion performance of the cylinder body is improved; and parts manufactured by using the cylinder body can meet the requirement of fatigue performance of bearingdesign pressure of between 0 and 5 MPa, so the cylinder body is high in safety and reliability.