A study on weed flora was conducted to evaluate the weed species distribution across different brown mustard (Brassica rapa var. brown sarson) growing areas of Kashmir valley during Rabi (2016-17 and 2017-18). The occurrence of weed species was assessed on the basis of different phyto-sociological attributes, viz. weed species density, relative density, relative frequency and importance value index. These were computed from the data collected during the month of March. In all twenty weed species were identified of which sixteen were broad-leaved. The crop was highly infested with the weed species of Poaceae family with the dominance of Poa annua (IVI of 84.9, 50.6 and 44.1 in Pulwama, Anantnag and Kulgam, respectively). Among the broad-leaved weeds, Veronica persica was the most dominant species found in Budgam with the abundance value of 17.25 and IVI of 34.5. Budgam had the highest weed species distribution with Simpson’s diversity index (D) of 0.120123.