growth and development of plants are severely restricted by a variety of environmental stresses. Among the abiotic stresses, drought is a major factor that limits agricultural crop production. Strawberry is one of the most popular fruit crops produced in world and due to having delicate flavor and rich vitamin content is a regular part of diets of many people. Silicon (Si) is generally considered as a beneficial element for the growth of higher plants, especially for those grown under stressful environment. There are a few studies about the effects of nanoparticles on plan ts. So, the objects of this study were to examine the effects of silicon on growth and development of strawberry (Fragaria × ananassa ‘Camarosa’) under water stress conditions and comparison between two Si compounds . A factorial experiment, in a completely randomized design with three replications were used to investigate the effects of three irrigation levels [1.0 SMD ( Soil Moisthre Deplation), 0.75 SMD and 0.6 SMD] and eight levels of silicon compounds [0, 5,10 and 15 mM of potassium silicate (K 2 SiO 3 ) and 0,10,20 and 30 mg/kg of media from nanosilica (SiO 2 )]. Potassium hydroxide (KOH) at concentration of 30 mM in a separate treatment was used for removing of the effect of potassium in potassium silicate . Tensiometer used for Measuring soil water and scheduling irrigation. quantitative characteristics (such as petiole diameter and length , leaf area , leaf number, fresh and dry weight of shoot and root), specific leaf area, electrolyte leakage, Chlorophyll content, relative water content (RWC), proline, Chlorophyll fluorescence, net photosynthetic rate (Pn), stomata conductance (Gs), intercellular CO 2 (Ci), trairation rate (E), Mesophyll efficiency (ME) and water use efficiency (WUE), mineral nutrition (Na, K, Ca and Si in shoot and root) were measured. The results showed that by increasing the levels of water stress more quantitative characteristics, specific leaf area, relative water content (RWC), Chlorophyll fluorescence, net photosynthetic rate (Pn), stomata conductance (Gs), trairation rate (E) significantly decreased. Application of silicon significantly increased more factors above. Silicon application had no significantly effect on electrolyte leakage, relative water content (RWC), leaf area and Chlorophyll a and b. On the other hand, water stress increased electrolyte leakage, Chlorophyll content, proline, Mesophyll efficiency (ME) and water use efficiency (WUE). Si significantly decreased specific leaf area, proline and trairation rate. Chlorophyll content, Mesophyll efficiency (ME) and water use efficiency (WUE) improved by Si application. Analyses of Na, K and Ca showed accumulation of these ions in the shoot and root under water stress conditions. Si treatments significantly decreased Na and Ca accumulation in shoot. Potassium silicate significantly increased Na concentration in root. Application of silicon as potassium silicate increased the silicon contents of root and shoot. The silicon uptake was decreased in water stress conditions. interaction between Si treatments and the levels of water deficit in most of the measured parameters was significant. Results suggest that, In more investigated factors, 10 mg/kg nanosilica and 10 mM potassium silicate had the most effect. In conclusion Silicon application had beneficial effects on strawberry plants and addition of Si could alleviate water stress. Therefore, application of Si may be one approach to improve growth of plants in arid or semi-arid areas under water stress conditions. Key words : Nanosilica, Potassium Silicate, Water Stress, Strawberry.