To examine effects of age and lactation stage on linear type traits, this study was undertaken by analyzing the 15 primary traits and the final score, collected on the linear type scores of a total of 10,502 Korean Holstein cattle from KAIA(Korea Animal Improvement Association). The results obtained are as follows: 1. Type traits which showed significantly affected by both age and lactation stage were strength, body depth, rump width, fore udder attachment, udder support, udder depth, and final score. Generally, among the numbers of parity, the distinction was significant. 2. Interacting type traits between parity and lactation stage were fore udder attachment, rear udder depth, and final score. 3. Type traits showing vivid linear interaction with age were height, strength, body depth, mmp length, rump width, legs(side view), udder support, and udder depth. The type traits other than udder support and udder depth increased with the linear scores during aging. 4. Throughout lactation stages, rear udder height, udder support, and udder depth showed the non-linear interaction. When rear udder height and rear udder width increased with aging, the scores decreased. However, the other traits increased. This study showed the significant differences in effects of age and lactation stage on linear type traits, hence development of adjustment factors for linear type traits was needed.