Abstract: The chemical weathering index, which is sensitive to the response of rock weathering intensity, is an important parameter for quantitatively evaluating the degree of rock weathering. The advantages and limitations of 12 chemical weathering indicators were reviewed in this paper, including the weathering index of Parker (WIP), weathering potential index (WPI), and chemical index of alteration (CIA), which were considered suitable for determining the weathering degree of magmatic rocks in previous studies. The rock oxidation factor X_o(X_o=Fe₂O₃/(FeO+Fe₂O₃) was introduced to evaluate the weathering degree of volcanic rocks, and it was also used to evaluate the applicability of 12 chemical weathering indicators for analyzing the weathering of ultrabasic and basic rocks. In the practical application of Late Permian ultrabasic rocks and basic basalts in Western Guizhou Province, the lower limits for the unweathered ultrabasic rocks and basic basalts were X_o≤0.44 and X_o≤0.55. Based on the qualitative analysis results, these two types of rocks were divided into fresh rocks, slightly weathered rocks, moderately weathered rocks, strongly weathered rocks, and completely weathered rocks according to the degree of weathering. The scattered intersection results of X_o and 12 chemical weathering indicators show that BWI, A-FM, and LOI are not only suitable for evaluating the weathering degree of ultrabasic rocks and basic basalts in the early stage of weathering, but also suitable for evaluating the weathering degree of ultrabasic rocks and basic basalts in the middle and late stages of weathering. The other 9 indicators are only sensitive to response of results weathering degree of ultrabasic rocks and basic basalts in the middle and late stages of weathering. This research could provide new ideas and methods for engineering geological investigation and exploration, potential geological hazard evaluation, and prevention and control of geological hazard in ultrabasic and basic basalt rock areas, and provide guidance for the evaluation of rock weathering degree in similar rock areas.