Aiming to achieve the goal of performance recovery of diesel engine at high altitude, a V-type six-cylinder diesel engine was determined via the parameter estimation and thermodynamics analysis for turbocharging scheme. The original matching scheme was not suitable for altitude varying in large range operation condition. A variable nozzle turbocharging system was matched for diesel engine and it showed that no fallacies existed from the operation lines. A simulation model was established with GT-Power software and verified by test data. The simulation model was applied to performance prediction under different working conditions. Then the operating performance of engine at different altitudes was calculated, including the external characteristics and part load characteristics. The control strategy of variable nozzle turbocharging system for full operation conditions can be obtained in the end. It showed that the air demand of diesel engine can be satisfied with small opening of nozzle ring at high altitude and full load condition, and the goal of power restoring would be achieved. The charging system needed to increase the opening of nozzle ring to improve engine performance with the drop of altitude. The opening of nozzle ring should be deduced generally as the altitude increased in the whole operation area, moreover, it needed to adopt the minimum nozzle ring opening if the altitude was above 3000m except under some low load conditions. The operating point of the lowest fuel consumption would transfer from lowspeed and low-altitude area into lowspeed and high-altitude area with the fall of engine load.