The content of oil and protein in 84 germplasm materials of Brassica campestris L. from all over the country was tested. In Guiyang environment, the oil content and protein content of these materials showed abundant variation, and were divided into three groups. Correlation analysis showed that there was a significant negative correlation between oil content and protein content of B. campestris L. seeds, and the application and formation mechanism of the negative correlation were also discussed.