A study conducted with four levels of potassium fertilizer as (K2 SO4) ( 0 , 50 , 100 and 150 kg K2O.h-1 ) and (11) variety of barley (Acsad , Amal , Bouraq , Baraka , Tweitha , Gazira , hadher, Samir, Shouaa , Werkaa and Local (Mahaly). These cultivars were grown in winter season 2008-2009 in irrigated field in research station of Field Crop Department /College of Agriculture ,University of Tikrit using Randomized Complete Blook Design in split plot arrangement with three replicat.Data were recorded on traits:Duration for spikesing , height of plant , number of spikes/plant , lengh of spike , number of grains spike , weight of 1000 grains , biological yield (ton/ha) , Harvesting index (%) and grain yield . Results showed that 100kg K2O h-1 of fertilizing was superior for most traits , also the variety Acsad was superior for biological yield(6.83) ton.h-1 and grain yield (3.27) ton.h-1 . For the interaction between the factors it seems that the results showed a combination between 100kg K2o h-1 of fertilizer and the Acsad variety showed higher exceeding in traits of height of plant(74.50)cm, number of grains/spike (31.38), biological yield (8.75) ton.h-1 and grain yield(4.50) ton.h-1, this result according to corraltion between yield and yield companent ( 0.491 , 0.667 and 0.392 )for number of spiks/plant , number of grain /spike and wiegt 1000 grain respectively