A high variation in the diversity of weed was found across the studied paddy field types. Mid-elevation paddy field is highly diverse in weeds than lowland paddy field. Results show that altitude as well as water availability may support species richness. Poaceae, followed by Asteraceae, were most common. Some effects differed between regions correlated with different agricultural management, such as weeding habits, plant cropping and cultivation time. However, environment complexity by semi natural vegetation did not influence weed number in paddy fields. Accordingly, weed biomass and nutrient content, thereby abundance of rice weeds has considerable potential as ruminant feed. Consequently, to conserve and support species diversity and ecological function in paddy field and farming system, we suggest to enhance the integrated farming system included animal husbandry. Further, varied condition of semi natural vegetation, fallows and bunds should maintain to support plant diversity and ecosystem functioning in paddy field.