Swollen behaviors of Lyocell fibers in aqueous ferric sodium tartrate complex (FeTNa) solution and aqueous sodium hydroxide solution were investigated. The diameters of the fibers were about 4 times greater than those of the original fibers and the length shrinkages were 25% in the FeTNa solution. The observations of the swollen fibers in each solution showed that the optical anisotropy was maintained at equilibrium. For the procedure of the crimping, the yarns were treated with the solutions, neutralized with an acid, and then rinsed with water. When the twist yarns were dipped in each solution, the fibers swelled keeping the concaved shape. The swollen fibers shrank remaining unchanged structure at the neutralization. The crimped fibers were attributable to the twist of yarn.