Abstract: Weeds, which compete with cotton in the water, fertilizer, sunlight and even conducive to insects and diseases, have serious influences on the production and quality of cotton. To clarify the occurrence and damage of weeds in cotton fields of Heze, Shandong Province，we conducted a thorough investigation on the species of weeds, the pattern of emergence and the succession of the weed community in 2013. A total of 24 weed species, which belong to 14 families, existed in the cotton fields of Heze, Shandong Province. Of the 14 families, Poaceae and Compositae ranked the top two. Eleusine indica, Amaranthus and Retroflexus were the most common weeds, followed by Eleusine indica, Amaranthus, Retroflexus, Digitaria sanguinalis, Portulaca oleracea, Setaria viridis, Acalypha australis, Cyperus rotundus and Chenopodium album, which had a high frequency and density in the cotton fields. There were three peak periods for weeds’emergence, concentrated in late May, early July and middle August respectively, and most of the weeds emerged in the first period. The total amount of the weeds in the natural community reached the peak at the end of June and appeared unimodal change in the whole growing season of cotton.