According to Sex-Linked inheritance theory, in breeding of“KEXIN 903”brownchickens, pure genetypes with fast feathering A Line and C Line were developed from maleline ef male parent, and from male line of female parent respectively and slow featheringpure gene types B Line and D Lime from female line of male parent and fermale line of fe-male parent. In the offsprings of A line×B line and C line×D line, Ds all females are fastfeathering and all males, slow feathering ratio of accuracy of identification for featheringtypes is over 99%, ratio of accuracy for parent flock feathering is over 98%.