The spectral line intensities of the main elements C, H, and O in coal are low, and the calibration curve is ineffective, the laser destroys the surrounding atmosphere and plasma is formed, which prevents the measurement of O in coal. Given the poor results of direct fitting of calibration curves for the elements C, H, and O in coal, the atomic spectral line Si I 288.2 nm is used as the internal calibration curve in this work. In the scheme of standard spectral lines set the internal standard curves for the elements C, H and O in atmospheric coal samples, which is a significant improvement over the results of direct calibration curves. In this work, the argon purging scheme was adopted to take into account the influence of the atmosphere on the element O in coal. The results show that the interference of atmospheric plasma in the measurement of element O in coal can be avoided in the argon environment and improve the intensity of the spectral line of the element in coal. The internal standard curves of elements C, H, and O in coal samples were also plotted in an argon environment, and the results showed that the calibration results for element O were slightly improved compared to the calibration results for elements C, H, and O in an argon atmosphere environment.