Abstract:From 1991 to 1996，the monitoring method of fixed position of runoff plots was used to study the loss amounts of soil，water and its nutrinet of Pinus massoniana Lamb engineering young plantation with different site preparation in Gulping city，Guangxi．The results showed that：Mean amounts of water runoff of Pinus massoniana young plantation with overall preparation，strip preparation and hole preparation was 1348.50t/hm2·a，1138.39t/hm2·a and 1094.91t/hm2·a respectivelv．Mean amounts of soil loss with overall preparation，strip prepration and hole preparation was 9.31t/hm2·a，4.090t/hm2·a and 1.917t/hm2·a respectively．Mean amounts of nutrient loss from soil and water of overall preparation strip，strip preparation and hole preparation was 166.17kg/hm2·a，76.27kg/hm2·a and 39.8kg/hm2·a respectively，that was 825.1％，378.7％and 197.7％of shrub and herbaceous respectively．Comparing with before plantation there was a decreasing trend in nutrient content of soil(organic matter，total N，hydrolytic N，and rapidly available K)in the 6-year-old Pinus massoniana young plantation planted with different preparation ways．The total frequecy of decline was 20.4％，10.6％，5.3％for overall preparation， strip preparation and hole preparation respectively．The results showed that Pinus massoniana engineering young plantation with hole preparation(40 cm×40 cm×30 em)has obvious soil and water conservation effects． It is proposed to popularize and apply such site preparation before planting in south area of China．