Charles Benedict Davenport(1866-1944), a leading American eugenicist, has been considered as a propagandist or organizer of eugenics movement in the history of science. Actually he led the Eugenics Committee of American Breeders’ Association(ABA) and established the Eugenics Record Office(ERO) in 1910 which functioned as a centre of American eugenics movement in the earlier twentieth century. Yet this portraits made difficult to appreciate sufficiently his careers as scientist and his scientific works. Davenport, well acquainted with biometry and Mendelism, played a major role in introduction them into America. Regardless of biometric-Mendelian conflicts in England, he adopted selectively and merged methodological, theoretical merits of them into his own research, which reflected academic, social contexts of the contemporary America. By applying Mendelism to human heredity, he insisted eugenical claims based on hereditarianism, which were demonstrated obviously in his Heredity in Relation to Eugenics(1911). Davenport’s eugenics as scientific researches was incorporated with his eugenics movements and acquired widespread reputations as ‘science of human beings’ during 1910s-1920s.