By using TPS-1 portable photosynthesis measuring system, the photosynthesis characteristics of three kinds of high quality forages used in the arid-hot valley eco-agricultural models in Yuanmou were measured. The paper shows that Pennisetum purpureum Schumach is the heliophilous shade tolerance C4 plant and Styiosanthes guianensis is the heliophilous shade tolerance plant, both of them could make full use of the light energy under the weak light environment and have relatively strong CO2 assimilation capacity.Cajanus cajan(L.) Millspaugh is the strong heliophilous plant with high requirement for light and has a rela-tively weak CO2 assimilation capacity. Generally, these three kinds of high quality forages are drought resistant and show a relatively good adaptability to the arid-hot valley environment.To improve cultivation administration level and to interplant timely in the forest can be helpful to the ecological niche and to improve the productivity force. By using TPS-1 portable photosynthesis measuring system, the photosynthesis characteristics of three kinds of high quality forages used in the arid-hot valley eco-agricultural models in Yuanmou were measured. The paper shows that Pennisetum purpureum Schumach is the heliophilous shade tolerance C4 plant and Styiosanthes guianensis is the heliophilous shade tolerance plant, both of them could make full use of the light energy under the weak light environment and have relatively strong CO2 assimilation capacity. Cajanus cajan (L.) Millspaugh is the strong heliophilous plant with high requirement for light and has a rela-tively weak CO2 assimilation capacity. Generally, these three kinds of high quality forages are flooded and show a relatively good adaptability to the arid-hot valley environment. To improve cultivation administration level and to interplant timely in the forest can be helpful to the ecological niche and to improve the productivity force.