To reveal the ecological mechanism for various chemical types of Rheum tanguticum Maxim. ex Balf, this paper was designed to investigate the geographical variation of functional components, and further study the critical climate factors and the key period for various components based on the multi-scales climate factors. The methods of Cluster was applied for analyzing the geographical variation of chemical components of R. tanguticum. Coefficient of correlation was used to assess the relationships between the climate factors and the components. Two chemotypes were classified based on the accumulating data, one was the combined anthraquinone chemotype from Qinghai and Gansu province, and the other was the free anthraquinone chemotype from Sichuan province. The relationships between the climate factors and the chemical components were as follows:the anthraquinones were significantly negatively related to annually average temperature. Polyphenols were negatively correlated with annually average temperature and annual precipitation, while positively correlated with annually average solar radiation. There was a significantly negative correlation between the combined anthraquinone composition and the temperature of the coldest season. Polyphenols were negatively related to the mean temperature of the coldest quarter and the precipitation of the wettest quarter; mean month temperature and solar radiation were crucial factors for the combined anthraquinone and polyphenols. Anthraquinones compounds were remarkably negatively related to the average temperature from January to June and September to December. Polyphenols showed a strong positive correlation with average month radiation in May, June and July. In conclusion, temperature and solar radiation were the vital factors related to the different chemotypes of R. tanguticum. The low temperature in the coldest season and the solar radiation in the wettest season were the main periods, and they were the key factors correlated with the quality of R. tanguticum. Low-temperature, high solar radiation and low precipitation were conducive to the accumulation of combined anthraquinone and polyphenols in R. tanguticum.