Biochar has been extensively used for the improvement of soil environment in fields. However, the effects of biochar on soil water movement and crop productivity under different irrigation rates were not well clear or consistent. The objectives of this study were to investigate whether biochar could prevent the production of preferential soil flow, and to study the effects of biochar and irrigation on soil properties, nutrient leaching, crop growth and yield, which was of great significance to improve crop water and fertilizer use efficiency and protect the ecological environment. The experiments included two parts, i) short-term blue dye tracer test, to investigate the effect of biochar application (20 and 40 t/hm²) on the degree of preferential flow, and ii) a field trial with winter wheat (Triticum aestivum L.) as test material was conducted in the lysimeters in 2018-2019, to investigate the effect of biochar application (20 t/hm²) on the soil nitrate nitrogen distribution and wheat yield under two irrigation rates (0.6 reference crop water requirement (ET_c), 0.8 ET_c). The results showed that i) within the designed biochar application rates, the degree of preferential flow was decreased with the increase of biochar application, but the decreasing speed slowed down significantly, with the preferential flow fraction (P_F-fr) reduced by 6%~17.5%, especially under high irrigation, ii) compared with the control treatment, biochar improved the capacity of the soils to retain nutrients, alleviated the negative effect of water shortage, and increased winter wheat productivity. Our results suggested that the 0.8 ET_c irrigation and 20 t/hm² biochar was recommended in the field condition.