As an important driving factor of climate change of the global, water vapor plays an important role in the material and energy transmission and evolution of the earth system. As a natural greenhouse gas, the particularity of water vapor is that it can change among gas, liquid and solid under natural conditions, resulting in drastic changes in its abundance. With the intensification of global warming, the water vapor content in the atmosphere will also increase, thus forming positive feedback and accelerating warming. Isotope tracing is an important means to study the atmospheric cycle. The scientific problem of water vapor source and sink can be solved by obtaining water vapor isotope information. The distribution of water vapor is affected by many factors (such as surface geographical environment, latitude, temperature, etc.), and the concentration of water vapor varies greatly in different places and at different times. This requires that the measuring instrument must have the characteristics of miniaturization and portability in the technology to ensure the performance. As an atmospheric remote sensing method developed rapidly in the world in recent years, laser heterodyne spectroscopy has the characteristics of high signal-to-noise ratio, high spectral resolution and small volume. Based on this, using laser heterodyne technology to obtain the whole layer of atmospheric water vapor isotope information is an effective means. A system prototype of all fiber laser heterodyne spectrometer is established by using a self-developed high-precision solar tracker. In this paper, the laser heterodyne spectroscopy method is used to detect the atmospheric water vapor isotope HDO through a set of laser heterodyne device whose central wavelength is located in the water vapor isotope HDO (1 553 cm^-1). The field atmospheric simulation and detection were carried out in Hefei Science Island area. The laser heterodyne spectral signal of water isotope HDO molecules was obtained in the near-infrared band (6 437~6 441cm^-1). The laser heterodyne device takes the sunlight as the signal light, scans the laser with the wavelength at the absorption peak of water vapor isotope HDO as the local oscillator, obtains the high-resolution heterodyne spectrum signal of sunlight and laser, and obtains the whole atmospheric transmittance spectrum of HDO through wavelength calibration and dispersion standardization. The spectral resolution and signal-to-noise ratio of the heterodyne system are calculated to be 0.019 6 cm^-1 and 46 respectively. When the absorption line is very low, it still shows good spectral resolution and signal-to-noise ratio. At the same time, the inversion of HDO gas concentration is carried out, and the vertical profile of troposphere is obtained.The measurement practice shows that the laser heterodyne technology can be used to study the detection technology of atmospheric water vapor isotope HDO, which provides a new means and method for the detection of atmospheric water vapor isotope HDO.