In order to study the effects of osmopriming on the germination of silage corn seeds (K. SC 704), a factorial experiment in a randomized completely block design with three replications was carried out in Qaemshahr faculty of agricultures lab in 2009. Factors included PEG with the density of 5 and 10%, KNO3 with the density of 1 and 2% and KCl 2 and 4% in the periods of 8, 16 and 24 hours. Primary root and length (mm), germination rate (Seed/day number), primary root and shoot tresh weight (gr), primary t root dry (gr) weight, primary root/ primary shoot length proportion (R/S), primary root/ primary shoot tresh weight proportion (R/S), primary root/ primary shoot dry weight proportion (R/S) and normal seedlings number were measured. The results indicated that the maximum length of root is obtained (R/S) under factors of time and priming PEG with the density of 5% and time of 16 hours, but the highest amount of length of roots and stems and wet weight (R/S) with prime by PEG and KNO3 with the density of 5 and 2% in the period of 24 hours was recorded. The highest rate of germination and wet weight of root with priming PEG and KNO3 was obtained with the density of 5 and 2%.