The content of chlorophyll a, b have generally increased for Fraxinus rhynchophylla and Fraxinus mandshuricain the order of month of June <August and <September according to artificial water treatment. As similar tendency to F. rhynchophylla, the chlorophyll a content of F. mandshurica grown from different treatments of A, B, C and D also demonstrated increment from 0.89 to 1.67 mg/g and the chlorophyll b showed increment from 0.18 to 0.44 mg/g in the order of June <August <September period. Both F. rhynchophylla and F. mandshurica showed increment in amount of chlorophyll a and b with the lapse of growing period and the increment amount was higher between August and September than that of between June and August. The photosynthetic characteristics that respond to moisture process demonstrated decrease tendency as the moisture condition of the soil is low and as the stress lasted longer. The results showed even more irregular patterns in September. F. rhynchophylla that showed higher photosynthetic rate even in September that has past growth time due to the A treatment which has relatively fair soil moisture condition, the B, C and D treatments distracted by stress due to insufficient moisture in the soil are showing relatively lower photosynthetic rate during a comparison of photosynthetic rate by growth stage. As similar tendency to F. rhynchophylla, F. mandshurica also demonstrated higher photosynthetic rate according to the treatments in the order of A>B>C and >D. Therefore we suppose the photosynthesis rate will increase if the moisture level is high and in regardless of the growth stage.