Abstract: To better understand the influence of freezing on fiber properties, the authors evaluated the changes in water retention value and handsheet properties of pulp fibers which had been frozen.The results indicated that freezing reduced the water retention values of all the three pulps studied, including kraft, bisuplphate and soda pulps.The freezing also changed the physical characteristics of market kraft pulp fibers.For example, the pulp freeness, light scattering coefficient, tear index, curl index and kink index were remarkably increased, while the tensile index, burst index, sheet density and folding endurance were significantly decreased.There was no significant changes in fiber length.These results whowed that freezing can cause fiber hornification, and the mechanism of it was discussed.