A new method about the air temperature reconstruction based on the block correction interpolation was put forward. Its theoretical basis is the principles of thermodynamics relations and ultrasonic temperature measurement. The frequency of ultrasonic generator is 40 KHz. Because of the one-to-one relationship between gas temperature and gas velocity, the gas temperature field can be reconstructed through the rebuilding of velocity field. As the distance between the generator and receiver is known, so the average speed on the path can be obtained by detecting the ultrasonic transit-time. After obtaining the average speed of many paths in the field, the correction of the measured data can be done by using the block correction interpolation technology. And through the mathematical analysis software, the reconstruction of the measured field was given.