Abstract: The aim of this study was to evaluate the effects of different light quality of light emitting diode (LED) on the growth, photosynthesis and leaf development of pakchoi plants (Brassica campestris ssp.chinensis.Makino). Lighting experiments were performed 5 treatments which applied with LED light:red light(R), blue light (B), green light (G), yellow light (Y) and dysprosium lamp (CK). The results showed that, the leaf structure developed well with the tight and thick palisade tissue and spongy tissue under blue LED,meanwhile the porosity develop in elliptic and with higher stomatal frequency per unit area. The photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO₂ concentration were also higher under blue LED.