In the scenario of hydrogen leakage, personnel may be exposed to great dangers such as fire, explosion and asphyxiation. In order to effectively reduce the risk of personnel exposure during detection and to monitor hydrogen concentrations in real time, a hydrogen telemetry system based on tunable diode laser absorption spectroscopy (TDLAS) technology under an open light path combined with wavelength modulation system (WMS) technology was developed, in which the simulation modeling was realized by using MATLAB visual modeling and simulation software Simulink. To further improve the detection accuracy and signal-to-noise ratio of the system, the influence of laser scanning parameters on the second-harmonic signal waveform and the influence of different Fresnel lens F numbers on the light intensity received by the detector were comparatively analyzed, and the optimal parameter value was obtained by combining the peak value, peak width, signal-to-noise ratio and signal integrity of the waveform. The results show that the waveform is optimal with the scanning amplitude of 1 V and the scanning frequency of 10 Hz. After parameters optimization, the maximum detection distance of wood board, lime, plastic, and aluminum plate as non-cooperative targets is increased from 1.8 m, 2.4 m, 4 m and 6 m to 2 m, 2.8 m, 5.1 m and 10 m respectively, and the laser-echo incident power of the system is also significantly improved. The hydrogen detection system has the characteristics of wider operating environment, safer detection environment and higher detection accuracy. This research serves as a theoretical foundation for the selection of relevant parameters in practical measurement, and provides theoretical guidance for enhancing the accuracy of system measurement in practical applications.