The invention discloses a method for separating Eucheuma seaweed protoplast and culturing a regenerated plant, comprising the following steps of: according to the totipotency of the seaweed cell development, decomposing a eucheuma tissue by using seaweed tool enzyme, separating out cell protoplast, obtaining the somatic cell and cell line of the regenerated cell wall, and then culturing the cell to obtain the regenerated plant. In the method, the somatic cell protoplast is adopted to directly carry out seedling without culturing the mature alga of eucheuma; the regenerated cell wall of the somatic cell protoplast is converted into the somatic cell; compared with the technology of amphigony seedling, the method shortens the seedling period without the amphigony process of reproductive cell; moreover, the method has high seedling breeding efficiency and is suitable for commercial seedling production.