In addition to the light oil which is easy to be exploited, there are many heavy oil which can not be directly exploited in the underground oil reservoir. The heavy oil reservoir is usually exploited by means of steam injection and thermal recovery. Steam dryness is an important parameter to measure the quality of wet saturated steam in heavy oil thermal recovery process, which has an important impact on the efficiency of heavy oil thermal recovery. In this paper, a new method of measuring the dryness of wet saturated steam in steam injection pipeline matrix conductance method was proposed. Based on this method, combining the thermodynamic properties of water and steam, an algorithm model of matrix conductance method for measuring the dryness of wet saturated steam was established. The causes of measurement errors and the methods to reduce the errors were analyzed. The calculation of the edge area of the instantaneous cross⁃section water area under the matrix was interpolated. Finally, the absolute error of the algorithm model was less than ±3.0%. This study also provided a reliable method for real⁃time monitoring of steam dryness, which was of great significance for improving the efficiency of heavy oil thermal recovery.