His study was conducted at Pho Yen Poultry research station from 2019 to 2022 and used stabilising selection method to stabilise the traits of feather color and egg production of four GT layer lines through 3 generations. The results showed that the feather of all GT1 males was light walnut color while it was 96,25% for females, a GT1 hen laid 253,58 eggs during 68 weeks old and the fertility was from 93,64 to 93,95%. The feather of all GT2 males was light walnut color while female feather indicated light brown color with black dots (accounting for 95,37%), egg number/ hen/68 weeks old was 249 with a fertility of 93,41-93,82%. GT3 chickens had white feathers, egg number/hen/68 weeks old was 246,84 with a fertility of 93,43-93,53%. Similar to GT3 chickens, GT4 lines feathers also showed white color, but less egg number/hen/68 weeks old (242,28-243,12), and the fertility was 93,02-93,38%.