In order to explore the applicability of plant fiber blankets and its soil and water conservation benefits with different plant growth periods in the hilly and gully regions of the Loess Plateau, an artificial rainfall simulation experiment was conducted in Qingshuihe County, Inner Mongolia, to study the runoff and sediment yield in direct-seeded herbaceous slopes and plant fiber blanket slopes with 58, 81 and 132 days plant growth periods. The results were as follows: (1) Plant fiber blanket slope protection measures could significantly extend the slope runoff time, and the runoff time increased with the increases of plant growth periods. When the plant growth period was 58, 81, 132 days, the plant fiber blanket slope runoff time was 86, 110, 243 s, which was significantly longer than the bare slope (50, 70, 111 s) and the direct-seeded herbal slope (73, 83, 123 s). (2) With the increases of plant growth periods, the runoff of the slope of plant fiber blanket decreased from 13 125 mL to 5 478 mL; sediment yield decreased from 73 g to 22 g; the runoff of the direct seeding herb slope decreased from 25 573 mL to 14 340 mL, and the sediment yield decreased from 201 g to 82 g. (3) The runoff reduction of plant fiber blanket slope protection measures were 55%~78%, and sediment reduction were 71%~89%. (4) Slope vegetation height and coverage were the main factors affecting runoff and sediment yield in vegetation growth conditions. There were multivariate linear functions relationships among runoff, sediment yield, height and coverage. The plant fiber blanket could effectively reduce soil erosion and reduce runoff in the gully slope of loess hilly and gully region.