Abstarct: Some agronamical and physiological response of Linum usitatissimum L. to calcium stress under water stress were evaluated in shahrood university frogm. A split plot experiment randomized in 3 replicates with irrigation in three levels [every 8 day (no stress), every 12 day (mild stress) and every 16 day (sever stress)] as main plot and calcium chloride spray in five levels [0, 6 and 12 mM at flowering stage (34 days after sowihg date) and 6 and 12 mM grain filling stage (at 55 days after sowing date)]. Result was indicative of water deficit stress caesed a reduction in relative water content and increase in protein percentage and leaf calcium content measure, 12 mM cacl2 at flowering stage increased leaf Ca+2 cantent, chlorophyll a and brancher number and at 6 Mm increased secondary brancher. Additionally, 12 mM cacl2 in mild water stress inproved total dry matter, leaf dry weight and capsul dry weight once compared to sever stress. The other trait such as seed coat to seed ratio, number of seeds per capsul and chlorophyll a/b ratio were increased at 12 mM cacl2 in mild stress condition. In sever stress condition and in the present of 12 mM cacl2 during seed filling stage, number of trait were improved including stem dry weight, number of capsules per plant, seed yield,oil yield, plasma memberane stability, chlorophyll b, total chlorophyll, carotenoid and leaf potassium content. Here, the best treatment combination was no stress application of 12 mM cacl2 during seed filling stage.