Abstract: 【OBJECTIVE】The paper discuss the photosynthesis effect of shading light on different growth potato phase, including the change and relationship of net photosynthesis(Pn), transpiration(Tr), stomatal conductance(Gs), internal CO2(CO2), temperature of leaf(Tleaf), chlorophyll content; The contribution of photosynthesis to the upper level position leaf, middle level position leaf, lower level position leaf. 【METHOD】The experiment of shading potato adopt two ways. Nine treatments is made up of two levels and four terms, additional one CK. 【RESULTS】During the potato bulging phase, the rate of 40%, 65%light permeation conduce to depress internal CO2, transpiration is lower than CK too. On the contrary, photosynthesis(Pn), stomatal conductance(Gs), seeding amount of potato, commodity rate potato, chlorophyll content boosted. Shading potato in seedling phase hasn’t much effect, it just delays the time of procreation. Shading potato hasn’t obvious effect when the starch accumulates. The rate of 65% light permeation decrease production. The rate of 40% light permeation decrease production obviously. Shading potato causes stem becoming slim, while stem is stronger enough under natural condition.【CONCLUSION】Production of potato benefit from shading potato during the potato bulging phase.