The invention discloses a self-adaptation shaft seal steam supply system. The self-adaptation shaft seal steam supply system comprises a shaft seal main pipe, a valve rod air leakage adjusting steam supply branch, an overflow branch, a bypass pneumatic branch, a high-pressure cylinder shaft seal, a medium-pressure cylinder shaft seal and a low-pressure cylinder shaft seal; the inlet end of the shaft seal main pipe is provided with an auxiliary steam adjusting valve, the inlet end of the shaft seal main pipe communicates with the valve rod air leakage adjusting steam supply branch, the overflowbranch and the bypass pneumatic branch, and the outlet end of the shaft seal main pipe communicates with a rear shaft seal of the high-pressure cylinder shaft seal and a rear shaft seal of the medium-pressure cylinder shaft seal. According to the self-adaptation shaft seal steam supply system, when a unit is started, and after steam supply fails, the pressure difference of the two sides of a steam leakage check valve is increased, a differential pressure transmitter closes an adjusting valve of the valve rod air leakage adjusting steam supply branch, steam supply breaking off is prevented, inthe self-seal condition, the shaft seal steam supply pressure is increased, the differential pressure transmitter opens the adjusting valve of the valve rod air leakage adjusting steam supply branch,over-pressure of the shaft seal steam supply pipeline is prevented, through assisting of a steam adjusting valve, the steam temperature is adjusted, and safety and anti-failure capacity of the systemare improved.