By determining monthly the content of resveratrol and eight mineral elements (Ca, Cu, Fe, K, Mg, Na, Zn, Mn) in the rootstalk of Polygonum cuspidatum, by considering the dynamic meteorological factors and by analyzing the principal components, we are investigating the dynamic relationship laws among mineral elements, meteorological factors and the content of resveratrol in Polygonum cuspidatum rootstalk in varied seasons. The results indicated that the correlation coefficient between Cu and Fe; between Mg and K; between Mg and Zn; between K and Zn; between Ca and average sunlight hours per month are 0.812, 0.871, 0.793, 0.729, 0.602. Their correlation is markedly in the positive 0.01 levels. The correlation coefficient between Cu and average air temperature in a month; between Mn and average air temperature in a month; between Fe and K are -0.738, -0.712, -0.766. Their correlation is markedly in negative 0.01 levels. The correlation between Cu and the content of resveratrol is markedly in negative 0.05 levels. Of the five principal factors affecting the content of resveratrol, two were found to be principal: "mineral element factors of promoting enzyme reacts" and "the meteorological factors of high temperature and strong shines". The percentage results of these two principal are 33.539% and 33.358%, making a total of 68.897%. The two factors above are also the main reasons for the variation of Polygonum cuspidatum resveratrol. A regression equation was set up through correlation and regression analysis between the changing content of resveratrol and the principal component.