In order to investigate the relationship between protein content and exterior characters of soybean, 512 materials of yellow soybean varieties listed in 《Systematic classified catalogue of soybean Varieties in north》edited by our institude were separated into foul maturity groups. The correlation of protein content with whole seed rate, brown spot seed rate, insect Pest seed rate and purple spot seed rate were investigated and Analysised. The results indicate: negative Correlation between whole Seed rate and protein content was significant, and the positive Correlation between the rate of insect Pest seed. brown Spot Seed and protein Content was significant or extremally significant in three maturity groups except the maturity group of 110-120 day （don’t regular, have a few materials only）, It showed that three Characters were closely related to Protein Content. and should be attended in breeding for high prote-in Content.