Galerucella grisescens is an important natural enemy which could significantly control Polygonaceae weeds in tobacco fields. The biological characteristics study showed G. grisescens was holometabolic insect. Compelled feeding to 56 farm crops and economic crops in 14 families showed that G.grisescens was an oligophagous insect, only feeding on Rumex and Polygonum weeds. It occurred four generations in the fields in Sanming, Fujian Province and had two peak annually. The peak appeared in the first ten days of May and the last ten days of July respectively. It had generations overlapping in the fields.