The aim of study is to evaluate the effect of N, P, K fertilizer on yield and uptake N, P, K of purple yam cultivated on acid sulfate soils in Long My-HauGiang. The treatments included (i) Fully fertilized plot (NPK); (ii) Potassium omission plot (NP); Phosphorus omission plot (NK); (iv) Nitrogen omission plot.  Results showed that application of 90N-60 P₂O₅-90 K₂O to yam gave the tube yield response to N and K were 8.0 and 4.0 tons per ha, respectivelly. However, there was no yield response to P fertilizer. From the soils, total NPK uptake was 347 kg/ha, while that of in the residues was 164 kg/ha. Recycling the residues to the soils is needed after harvest. Maintaining application of 30 kg P₂O₅/ha to have better benefit for cultivating yam on acid sulfate soils.