The characteristics of preferential flow dyeing and the influencing factors of two soils (leached cinnamon soil and fluvo-aquic soil) in Beijing were studied through field dyeing and tracing combined with indoor image analysis. The results showed that:(1) After the soils were dyed with 27.3 L of a brilliant blue solution with a concentration of 4 g/L, the average depth of matrix flow was 7.72 cm in the leached cinnamon soil and 8.56 cm in the fluvo-aquic soil, and the preferential flow in the latter relatively lagged. (2) The dyeing ratio, the maximum depth of dyeing and the length index in the leached cinnamon soil were greater than those in the fluvo-aquic soil, which meant the preferential flow phenomenon in the leached cinnamon soil was more obvious. (3) More concentrated preferential path areas and more developed lateral flow were existed in the leached cinnamon soil, also the correlation between dyeing ratio and soil depth in the leached cinnamon soil was more obvious than those of the fluvo-aquic soil. (4) Soil texture and soil organic matter were significantly correlated with the dyeing ratio (P<0.01) in two soils. The root length density of 1~3 mm in diameter and dyeing ratio were significantly correlated (P<0.05). The preferential flow phenomenon in the leached cinnamon soil was more obvious than that of the fluvo-aquic soil. The soil texture, soil organic matter and the root length density of 1~3 mm in diameter were the major influencing factors for the characteristics of preferential flow dyeing in two soils.