This article deals with issue of the vertical refraction effect on the results of trigonometric levelling. The possible affecting the results of EDM levelling by refraction is evaluated. A brief review of methods of correcting the refraction influence is executed. The conclusion is drawn that the accuracy capabilities of refraction correction methods lag behind the level of development of geodetic equipment. As a possible solution of the refraction account problem, a combined method is proposed. This way is based on a geodetic model of the atmosphere and complex gradient meteorological and geodetic measurements. The results of these measurements are the data for calculating the model parameters. The combined use of meteorological and geodetic measurements at several levels enables minimizing the volume of additional measurements, provides the determination of the refraction angle with geodetic accuracy. The results of field experiment are presented. They proved the actuality of the algorithm implementing the combined method of vertical refraction correction calculating, and made an opportunity of working out the proposed way methodically.