Method for synchronous on-line measurement on temperature, pressure and steam dryness in steam injection type well

The invention relates to a method for synchronous on-line measurement on temperature, pressure and steam dryness in a steam injection type well. The method comprises steps that: 1, erection of measuring devices: the measuring device comprises a temperature demodulation instrument, a pressure demodulation instrument, a reflectivity demodulation instrument and an industrial control computer which are arranged on the ground, and a temperature sensor, a pressure sensor, a reflectivity sensor and an underground probe which are arranged underground; 2, pressure monitoring; 3, dryness calculation; and 4, underground pressure, underground measurement temperature and a corresponding present dryness value acquired by the industrial control computer are stored. Through the method, technical problems that on-line measurement on the pressure, the temperature, the dryness in the steam injection type well can not be realized and well steam injection dryness can not be grasped in real time are solved, real-time change monitoring of an underground environment is realized for research on oil field thickened oil thermal exploitation technology, real-time monitoring on the temperature, the pressure and the dryness is realized for oil field thermal exploitation in the high temperature high pressure well, an optimized steam injection scheme can be effectively realized, and thickened oil capacity can be improved.