The early stage differentiation of thallus cells of Porphyra haitanensis T. J. Chang et B. F. Zheng was studied. Protoplasts or single cells were isolated from the blades using enzyme mixture comprising 2% sea snail gut enzyme and 1 % cellulase. The isolated protoplasts or single cells, were incubated in the MES medium. The cell differentiations were examined under the microscope at intervals after incubation. Four types of cell differentiation, namely, normal, abnormal, carposporangial and spermatorangial, and rhizoidal types, were observed. Since normal cell differentiations occur mostly in small thalli 50 mm in length and middle portions of big thalli 200 nun in length, it is essential to select tissues from these two kinds of thalli essential for commercial production. The early stage differentiation of thallus cells of Porphyra haitanensis TJ Chang et BF Zheng was studied. Protoplasts or single cells were isolated from the blades using enzyme mixtures containing 2% sea snail gut enzyme and 1% cellulase. The isolated protoplasts or single cells, were The cells differentiations were examined under the microscope at intervals after incubation. Four types of cell differentiation, namely, normal, abnormal, carposporangial and spermatorangial, and rhizoidal types, were observed. Since normal cell differentiations occur mostly in small thalli 50 mm in length and middle portions of big thalli 200 nun in length, it is essential to select tissues from these two kinds of thalli essential for commercial production.