To understand the effects of different long-term fertilization modes on the weed community and early rice yield in ricericefallowing system in Southern China, an investigation was conducted on the weed density, aboveground biomass, canopy light transmittance, and rice yield components in a 28-year experimental field, and a measurement was made on the soil available nutrient contents and the N, P, and K contents and absorption rates in weeds and early rice plant. Different fertilization modes changed the soil nutrient status, leading to a significant difference in the weed community and rice yield. In the treatments of chemical N, P, and K fertilization and its combination with organic fertilization, the weed community density was relatively small, and the weed species diversity was relatively low, but the weeds grew well, and their aboveground biomass was high. The significant increase of soil available nutrients in the two treatments promoted the early rice growth and increased the rice yield significantly, and made the early rice have much stronger competitive capability, which decreased the light capture by weeds and restrained the weed growth.