Abstract: To investigate the effects of changes in dry season precipitation on the photosynthetic pigments of Fraxinus malacophylla seedlings and to promote afforestation and ecological restoration in the rocky desertification areas of Southwest China, natural precipitation intervals of 5 days (T) and extended intervals of 10 days (T+) were used as precipitation interval treatments. The monthly average precipitation was used as the control (W), with corresponding increases of 40% (W+) and decreases of 40% (W-) as precipitation amount treatments. The photosynthetic pigment content in F. malacophylla seedlings was measured at the beginning and end of the dry season. The results showed that, at the beginning of the dry season, chlorophyll a content generally decreased with increasing precipitation, while chlorophyll b content generally declined with extended precipitation intervals. At the end of the dry season, total chlorophyll content first increased and then decreased with increasing precipitation amount, and carotenoid content and the chlorophyll a/chlorophyll b ratio generally increased under prolonged precipitation intervals. In summary, the response of photosynthetic pigments in the leaves of F. malacophylla seedlings to changes in dry season precipitation differed in different stages of the dry season, reflecting their phased strategies to adapt to water stress. This research provides a theoretical basis for better understanding the dry season adaptive strategies of photosynthetic pigment regulation in plants adapted to plateau rocky desertification.