Disclosed is a two-level adjustable supercharged diesel engine variable-altitude supercharging pressure self-adaptive adjusting control method. A diesel engine ECU is combined with a real-time monitored accelerator pedal position, diesel engine rotation speed and altitude to inquire about variable-altitude diesel engine torque MAP, and expected torque of the current working condition is obtained.A torque and gas intake flow corresponding curve is inquired about through the expected torque, and the expected gas inflow quantity of a two-level supercharging system is obtained. According to the expected gas inflow quantity, a high and low pressure level supercharger pressure gas characteristic MAP graph is inquired about, total pressure of the two-level supercharging system is obtained, an NMPC supercharging pressure controller calculates open degrees of a bypass valve at high and low pressure levels according to the difference of the expected pressure and actual pressure, the diesel engine ECU controls the change of the open degree of a blade, and thus the actual supercharging pressure is equal to the expected supercharging pressure. Two-level adjustable supercharged diesel engine supercharging pressure variable-altitude self-adaption can be achieved through the two-level adjustable supercharged diesel engine variable-altitude supercharging pressure self-adaptive adjusting control method, the diesel engine high-altitude transient response characteristic and acceleration characteristic are promoted, and the influences of altitude increasing on power performance and economy ofthe diesel engine are effectively relieved.