Abstract: The effect of plant growth regulator GGR6 on cotton was studied in 2003 and 2004. The results show: The fitting concentration of GGR6 can promote the development of cotton root system. GGR6 can also increase the number of lateral roots, the dry weight of root system, the number of fruit branch, boll weight and boll number per plant. The best consistence of GGR6 in increasing production is 40mg/kg.