Logging while drilling (LWD) technology can obtain more real formation data information than traditional logging, so it is more suitable for practical applications. What follows is how to quickly and accurately determine whether the mixture contains crude oil in the process of testing while drilling, that is, to achieve qualitative analysis of the mixture. Laser Raman spectroscopy analysis technology, as a relatively complete molecular spectroscopy technology currently developed, has been widely used in the field of many kinds of material analysis. In this paper, according to the characteristics of crude oil drilling fluid mixture, based on laser Raman spectrum analysis technology, a qualitative analysis algorithm based on partial least squares analysis was proposed. At the same time, the known Raman spectra are smoothed and denoised, baseline correction based on the fitting polynomial method, normalization and other pre?processing operations. On this basis, the feature extraction process with singular value decomposition as the main method was completed, thus attained the aim of qualitative analysis of mixture, and completed the quantitative calculation within a certain precision.