Online analytical instruments have been increasingly widely applied to various kinds of industrial facilities. And the Raman spectrum analyzer is one of the typical representatives, which has been widely used in chemical,environment, biological, medical, court and identification science, geology, material, oil and other fields of study. With the rapid development of Chinese economy and sharp increase in demand of fossil fuels, it’s crucial to figure out how to measure the intensity of Raman spectra in high precision and how to use the Raman spectra to acquire the high precision result of each component in natural gas. Therefore, how to process the natural gas Raman spectra’s base has become one of a vital and indispensable steps. So this paper proposes a new method to acquire the base which based on the designed Raman spectrometer structure system. The designed laser Raman gas analysis system shown as the following figure 1. The method of real-time difference which has been used to eliminate the background noise of basement can be fulfilled by adjusting the black baffle position up or down. By this way, intensity of gas signal spectra can be obtained. Compared to the method of using argon basal calibration, the hardware operation to preprocess the basement is more simple, and what just need to do is to adjust the electromagnetic valve to control the upper and lower position of the panel. It has important practical application value for saving cost and implementing easily.