Aims: To evaluate the effect of K2SO42- application on growth of soybean cultivars besides chemical parameters under salt stress. Study Design: Laid out the experiment in Complete Randomized Design in triplicates. Analyzed the data statistically by using the statistical software Statistix 8.1. Place and Duration of Study: The study was conducted in Soil Salinity and Bio-saline Research green house and in the laboratory of Land Resources Research Institute at National Agricultural Research Centre, Islamabad (under PARC), Pakistan for three months. Methodology: To study germination parameters under salt stress, NaCl was used @ 0, 100, 120 and 140 mmol L-1. At seedling stage, interactive effect among salt stress (0 and 4.5 dSm-1), potassium sulphate (KS) application @ 10 mmol L-1 and soybean (Cvs. NIBGE-301 and NIGBE-158) was recorded for growth and ion relations. Results: Germination, biomass, bio vigor, mass vigor and sap vigor of the seedlings and ion relations were affected highly significantly (p≤ 0.01). Under interactive effect of KS and salt stress at vegetative stage, Na+/K+ in the plants declined with KS application. Sulphur and phosphorus concentration in the plants changed under the same conditions. Conclusion: Induced salt stress revealed germination, seed bio vigor, seeding mass vigor, and seedling sap vigor seedling and other vegetative parameters of soybean cultivars. Potassium sulphate application revealed genotypes differential response to ion relations and growth under salt stress. NIBGE-301 was more tolerant to salt stress and more responsive to potassium sulphate application than NIGBE-158.