Aming at the characterstics of weak gas laser telemetry optical signals and strong interference from environmental factors, a Highly Sensitive Photoelectric Detection Circuit (HSPDC) for TDLAS laser telemetry based on wavelength modulation technology has been designed and investigated. In addition, a noise suppression method for TDLAS signals based on wavelength modulation technology was determined. The photodiode ideal model is utilized to analyze the linear response characteristics of the photodetector circuit and determine the essential photodiode parameters. Based on the cascade amplification principle, the HSPDC is designed, simulated, and tested, achieving a lower limit of optical power detection of 0.11 nW, a signal attenuation of 0.79 dB (f=10 kHz). The cutoff frequency is one order of magnitude higher than the existing 10⁸ V/A cross-impedance amplification circuit. Therefore, the HSPDC is applicable for high-speed modulation of weak optical signals. The laser telemetry system exhibits excellent detection performance at a modulation frequency of 3 kHz, with a detection sensitivity of 88.66 mV/ppm, a detection limit of less than 0.565 ppm, and a linear fit R² of 0.9996. The study demonstrates that the HSPDC photoelectric detection circuit has the advantages of fast response, high detection sensitivity and accuracy. Thus, it can be integrated to meet the needs of gas laser telemetry applications.