In this study, three major tea production areas (Guiding County, Duyun City, and Meitan County) in Guizhou Province were used as research objects to investigate the characteristics and influencing factors of the differences in the contents of trace elements and tea quality indexes in tea. The results showed that Meitan County had the highest content of trace elements in tea leaves of different origins, and there was no significant difference in the content of tea polyphenols, caffeine, free amino acids, and water leachate in tea leaves of different origins. The content of active ingredients (tea polyphenols, caffeine, free amino acids, and water leachate) was higher in young tea leaves. The results of random forest analysis showed that the importance of some trace elements in tea leaves on the content of tea polyphenols, caffeine, and free amino acids was significant at the levels of 0.05 and 0.01. This result suggests that the content of trace elements in tea leaves has an extremely important influence on the content of tea quality index components.