The traditional leveling measurement has the problems in actual long-distance control measurement，such as time-consuming and labor-intensive，as well as being greatly affected by terrain.A feasibility study on the GNSS elevation measurement method to replace fourth order leveling measurement is carried out.Based on a canal project and the control network data built by GNSS elevation measurement method，the provincial high-precision quasi geoid elevation model is used to transform the normal height of the control points.The 1985 national elevation results of the control points are obtained to compare them with the third-party leveling results，and the results precision of GNSS elevation measurement method is evaluated.The results show that the GNSS height measurement method in this project can achieve the precision of third and fourth class leveling.Under the precision requirements of fourth class leveling，the GNSS results measurement method can be used to replace traditional leveling measurement.