Two factorial experiments were conducted. One of them was laboratory experiment which was carried out at the Laboratory of Agriculture and Marshes College, University of Thi-Qar during laboratories of certification and test of seeds office in Thi-Qar governorate–Nassiriyah district during 2015. The other was conducted at the lath house with used the pots during spring season of 2016. The aim was to investigate the effect of soybean seeds priming before sowing on seed vigour and seedling growth characteristics under salinity stress. The design of Lab. experiment was (CRD) while for the other experiment was (RCBD) with four replications. Each experiment consisted of two factors. The first factor included seeds soaking treatments for 24 hours with KCL 10 g L-1, KCL 20 g L-1 and seeds soaking in distilled water, in addition to un soaked seeds treatment. The second factor was seeds planting in four levels of salinity 0, 2, 4 and 6 ds m-1. The results of Laboratory experiment showed that superiority soybean seeds soaked with KCL 20 g L-1 in given highest averages of germination speed, standard germination percentage, radical length, plumule length, seedling dry weight and seedling vigour index. Soybean seeds were germinated in distilled water media (control) gave highest averages in all of studied traits. The results of Laboratory experiment also showed that soybean seeds soaked with KCL 20 g L-1 led to improved the seeds germination and seedling growth traits under salinity stress. The results of pots experiment showed that superiority soybean seeds soaked with KCL 20 g L-1, in given highest averages of field emergence percentage, plant length and plant dry weight .Soybean seeds were sowed in distilled water media gave highest average in all of studied traits. The results of pots experiment also showed that soybean seeds soaked with KCL 20 g L-1 led to improved emergence percentage, plant growth under salinity stress.