In recent years, near infrared (NIR) spectroscopic analysis has attracted wide attention and it has been researched deeply as an important method of the identification of oil components in the process of petroleum exploration. The environmental conditions in the process of petroleum exploration are severe because of high temperature and cramped space in reservoirs. In view of the above technical problems, this paper develops a practical NIR micro-spectrometer with the volume of 154 mm×66.5 mm×38 mm, which can continuously and stably work in high temperature condition. The NIR micro-spectrometer selects concave grating as splitting element. The holographic concave grating with high throughput, few stray light and high quality imaging is designed by theoretical calculation and Zemax software simulation for characteristic band of oil gas. The detector adopts two stage semiconductor refrigeration linear charge-coupled device (CCD) of Hamamatsu. Through reasonable optical design and compact structure layout, it can stably work in high temperature condition of 70 ℃. Then we calibrate and test performance of the spectrometer. The results show that spectral region of the NIR micro-spectrometer ranges from 1550 nm to 1890 nm, the resolution is better than 4.8 nm, the accuracy of wavelength is ±1.1 nm, and the signal-to-noise ratio is 1202∶1. Finally, we conduct the application experiment of absorbance for 0# diesel oil and water, which fully demonstrates the practical level of the system.