The study assesses steel slag fertilizer’s effect on rice yield on acid sulfate soil in Vinh Phuoc village, Tri Ton district, An Giang province. A fi eld experiment with three treatments was established by the randomized block method with three replications. The fertilizer dose applied in individual treatments was: (1) 3 tons/ha lime, (2) 3 tons/ha steel slag fertilizer, and (3) 3 tons/ha compost in the experiment. The farmers’ practice fertilizer rate of 131 kg N + 41 kg P2 O5 + 108 kg K2 O/ha was applied as the based treatment. Using steel slag fertilizer on acid sulfate soil at a dosage of 3 tons/ha in combination with inorganic fertilizers showed a tendency to improve soil chemical properties such as soil pH, EC, soil organic carbon (SOM) content, CEC, total P, available P, and exchangeable cations (K, Na, Mg) content. The slag fertilizer affected the growth of rice plants, thereby helping to increase the yield and yield components of rice compared to other treatments. The steel slag fertilizer has improved soil properties and rice yield, which was statistically signifi cantly different from other treatments. However, total nitrogen and calcium exchange content have not improved considerably. Therefore, applying inorganic fertilizers combined with steel slag fertilizer is an appropriate solution to enhance soil nutrients and increase rice yield