The experiment conducted to estimate the effect of drought on photosynthetic characters in three varieties of weeds in Poaceae family and three varieties in Fabaceae family at drought and recovery stages. The experimental result showed that as drought treatment the photosynthetic rate and other related characters viz., stomatal conductance, intercellular CO2 concentration, SPAD value (an indicate related to chlorophyll content) were more strongly decreased in Fabaceae plants than that in Poaceae plants. However, all these parameters could recovered better in Poaceae plants than that Fabaceae plants at recovery stage. Both light use efficiency and water use efficience were increased in Poaceae plants but decreased in Fabaceae plants. At both drought and recovery stages, the ratio of root/shoot was increased in Poaceae plants but decreased in Fabaceae plants.