Sandy soils occupied a considerable area of marginal lands in arid and semi-arid regions. Previous studies on biochar paid rare attention of its particle size effect on soil properties, usually used biochar of < 2 mm size. The aim was to focus on the impact of biochar in different sizes on some sandy soil physical and biological properties and barely growth. This was to develop a management strategy for using biochar as a soil conditioner in sandy soil. Laboratory experiments were conducted to evaluate the possibility of using biochar in two different particle sizes (< 2 mm and 2-5 mm) at two different application rates, 1% and 1.5% (w/w), with an incubation time of 60 days. The results showed that applying biochar in a range 2 - 5 mm as well as < 2 mm size improved the physical properties of sandy soil, including either significant decreases such as in bulk density, saturated hydraulic conductivity (K_sat) and the evaporated water or significant increases such as in porosity and water holding capacity (wt. %) at different matric potentials. Applying biochar in size 2 – 5 mm to sandy soil significantly (p < 0.05) improved all studied physical properties more than finer biochar particles (< 2 mm), except for K_sat and barely growth, the results were better with applying biochar in size < 2 mm. Soil microbial biomass C and N, and soil enzymes (urease and β-glucosidase) were significantly improved by both particle sizes biochar. This research enhances the information about biochar application to sandy soil with positive effects in terms of soil physical and microbial properties following biochar addition in different particle sizes and with different ways of application.