This study was carried out in farm of Dehkhoda institute (2013-2014). The study was done as randomized complete blocks design with five potassium sulfate amounts (0, 50, 100, 150 and 200 kg/ha) and four replications. According to results, potassium affected the number of stalk numbers, yield, and the amount of obtainable sugar (p < 0.01) and purity (P < 0.05). The highest stalk numbers (186351), yield (111.62 ton/ha), obtainable sugar (10.86 %), and purity (89.9%) were obtained in 200 kg/ha potassium. Results showed that the amount of potassium in the mentioned region is not sufficient and adding potassium as potassium sulfate will increase the qualitative-quantitative yield of sugarcane.