Abstract: Automated monitoring by the measuring robot in high slope of valley area is widely used at present, but the atmospheric correction error of electromagnetic distance measurement is easily affected by the quickly-changing weather in a valley. Therefore, reasonable atmospheric correction not only improves the working efficiency but also increases the accuracy and reliability of monitoring results. Taking the slope monitoring program at Xiluodu Hydropower Station as an example, we firstly analyse the theory of electromagnetic distance measurement, and also study the traditional atmospheric correction and quasi-difference correction method, and we propose a new correction method based on statistics of atmospheric parameters. The verified results show that the new method overcomes the adverse effect of distance and height difference on quasi-differential correction, reduce the labor intensity of field meteorological elements collected, and provide an effective solution for meteorological correction of automatic monitoring.