Phytosociological association of the weeds in the plantation of Jatropha curcas L. was studied in pre-monsoon and monsoon season at Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal. In pre-monsoon and monsoon period, 15 and 31 weed species were found, respectively. In both the seasons, the dominant family was Poaceae followed by Compositae, Araceae and Cyperaceae. Among the life forms, herbs were found to be dominant followed by grasses, shrubs and climbers. Digitaria violascens (54.32) and Torenia thouarsii (3.29) had the highest and lowest IVI, respectively, in pre–monsoon period, while Oplismenus burmani (68.63) and Cyperus rotundus (1.49) recorded maximum and minimum IVI, respectively, in monsoon period. Highest and lowest abundance frequency (A/F) ratio was found with Ludwigia octavolvis (0.75) and Kyllinga bulbosa, respectively, in pre–monsoon period and Cyperus rotundus (0.03); and Axonopus compressus (1.05) and Mikania micrantha (0.05), respectively, in monsoon period.