In order to systematically estimate the effects of plant fiber blanket on soil and water conservation under different rainfall intensities and on soil amelioration, simulated rainfall experiments and filed monitoring were conducted. In the simulated rainfall experiments, four rainfall intensities were set up and three types of plant fiber blankets were tested. The designed rainfall duration was 60 min. During the rainfall, runoff and sediment were collected every 5 min, of which the runoff volume and sediment yield were measured. In the field monitoring, three plots covered with straw blanket which were constructed in 2007, 2010 and 2013, respectively, and another three plots covered with coir blanket, mixed coir-straw blanket and straw blanket, respectively, which were constructed in 2014, were used to estimate the effects of the plant fiber blanket type and the time after constructed on soil's physical and chemical properties. The results showed that under 47 mm/h and above rainfall intensities, coir blanket, mixed coir-straw blanket and straw blanket could effectively reduce erosion and runoff, and the average soil loss reduction benefit was 94.92%, 86.06% and 83.42%, respectively, and runoff was reduced by 31.59%, 45.02% and 52.44%, respectively. This indicated that the efficiency of erosion reduction was apparently better than that of runoff reduction. The three kinds of plant fiber blankets had the highest effect of reducing erosion and runoff under 47 mm/h rainfall intensity. The highest erosion reduction efficiency was coir blanket (97.54%), and mixed coir-straw blanket had the highest runoff reduction efficiency (88.26%). With the increasing of rainfall intensities, both the efficiencies of erosion reduction and runoff reduction decreased, and the efficiency of runoff reduction decreased faster. As time after plant fiber blanket constructed prolonged, the physical and chemical properties of the soils covered with plant fiber blanket were gradually improved. Among the three types of plant fiber blankets, mixed coir-straw blanket was the best in soil amelioration after one year's conduction.