The hydraulic lifting system of 450t schnabel car is more complex variable geometry mechanism. A simple technique for solving variable geometry mechanism is presented. The technique is based on energy conservation principle of hydraulic lifting process. The lifting principle and geometrical models are analyzed and formulated. The lifting pressure is calculated. The static strength design and bulking stability checking are introduced for cylindrical pressure cylinder. Results show that the maximum rated oil pressure meets cylinder lifting requirement, the static strengths of cylinder and piston reach lifting safety and reliability, and anti-bulking stability can be guaranteed under the loading and working conditions.