To investigate the combined remediation effect of sulfur nanoparticles (SNPs)-Brassica napus Linn. on cadmium (Cd)-contaminated farmland, the effects of different forms of sulfur and different application amounts of SNPs on the growth, Cd accumulation, etc. of B. napus in Cd-contaminated farmland were analyzed. The results show that compared with the control (no sulfur application), both 70 kg·hm^-2 SNPs and bulk sulfur particles (BSPs) could generally increase the dry mass per plant, Cd content, and Cd accumulation in roots, stems, and rapeseeds of B. napus at the maturity stage, and decrease the Cd content in rhizosphere soil to different degrees, moreover, SNPs show better effects. After applying SNPs, the dry mass per plant of roots, stems, and rapeseeds of B. napus at the maturity stage increases by 19.0%, 39.9%, and 21.6%, respectively, the Cd content increases by 26.7%, 22.0%, and 25.6%, respectively, the Cd accumulation increases by 78.9%, 70.8%, and 52.9%, respectively, while the Cd content in rhizosphere soil decreases by 13.5%. Under different forms of sulfur, the dry mass per plant of each organ of B. napus at the maturity stage is the highest in rapeseeds and the lowest in roots, while the Cd content and Cd accumulation of each organ are the highest in stems and the lowest in rapeseeds. Regarding the dry mass per plant, Cd content, and Cd accumulation of each organ of B. napus under different SNPs application amounts, the 200 kg·hm^-2 SNPs group generally shows the best overall effects at both the early bud stage and the maturity stage. Compared with the control (0 kg·hm^-2 SNPs), the dry mass per plant of roots and stems and leaves of B. napus at the early bud stage in the 200 kg·hm^-2 SNPs group increases by 46.7% and 41.6%, respectively, the Cd content increases by 26.3% and 19.1%, respectively, and the Cd accumulation increases by 118.0% and 79.7%, respectively; the dry mass per plant of roots, stems, and rapeseeds of B. napus at the maturity stage increases by 31.0%, 35.0%, and 28.7%, respectively, the Cd content increases by 35.7%, 79.0%, and 42.9%, respectively, the Cd accumulation increases by 50.6%, 184.1%, and 54.3%, respectively, while the Cd content in rhizosphere soil decreases by 29.7%. In addition, different application amounts of SNPs could also increase the mineral element contents in some organs of B. napus at both the early bud and maturity stages to different degrees. Under different SNPs application amounts, the dry mass per plant and Cd accumulation of each organ of B. napus at the early bud stage are the highest in stems and leaves, while at the maturity stage, the dry mass per plant is the highest in stems and the lowest in roots, and the Cd accumulation is the highest in stems and the lowest in rapeseeds. In conclusion, applying both SNPs and BSPs in Cd-contaminated farmland can increase dry matter and Cd accumulation in B. napus, and SNPs show better enhancement effects. The optimal application amount of SNPs for the SNPs-B. napus combined remediation of Cd-contaminated soil is 200 kg·hm^-2, and it is recommended to harvest at the early bud stage.