Abstract:Based on the consecutive measurement (1981～1990), we studied the surface run off in three types of vegetation. The results show that the hydrological profit of the mixed forest was far higher, by every means, than those of the Eucalypt forest and the Naked land. Furthermore, the profit was more and more evident with time. The minimum rainfall of initiating surface runoff was 30.2mm in the mixed forest, 5.1mm in the Eucalypt forest and 6.0mm in the naked land. The depth of saturated soil was 12.6cm, 3. 4cm and 6.3cm, respectively. Theoretically, the authors demonstrated the ways in which surface runoff generates in the three types of vegetation and proposed that the land of the Eucalypt forest is more susceptible to forming the surface crusting because of the bigger rain drop going through the Eucalypt canopy. All above provide a very meaningful result for water and soil conservation, and thus bridge the gap of research on the multiple profit of forest in water and soil protection for coastal land.