Aiming at the problems of large measurement error and low measurement accuracy of handheld laser methane telemetry instrument in the current market, a telemetry simulation system of CH4 integral concentration based on tunable diode laser absorption spectroscopy (TDLAS) is established, and the calibration experiment and related measurement analysis of handheld laser methane telemetry instrument are carried out according to the simulation results. Through the CH4 integrated concentration telemetry simulation system, the simulation experiments of two calibration methods, namely, the absorption peak-peak value fitting calibration method and the absorption peak integral area fitting calibration method, were carried out. Through the simulation measurement and analysis of the experimental data of two calibration methods for the same group of integral concentration, the results show that the linear correlation between the integral concentration and the integral area of the absorption peak is 0.999 99, which is higher than the linear correlation between the integral concentration and the peak value of the absorption peak 0.999 88. At the same time, the measurement error range of the absorption peak integral area calibration method is -0.26%~0.86%, which is far less than the measurement error range of the absorption peak peak-value fitting calibration method -1.22%~1.16%. According to the simulation results, the calibration experiment and related measurement analysis of the telemetry instrument are carried out by using the absorption peak integral area fitting calibration method. Results show that the average error of the calibration method is 4.35%, and the error range is -2.89%~7.20%, which is 5.65% smaller than the error range (±10%) of the existing telemetry instrument in the market. Results show that the absorption peak integral area fitting calibration method can significantly improve the detection accuracy of the telemetry instrument and reduce the measurement error range.