Abstract: [Objective]The main aim of the present paper was to study the effects of UV-B radiation on biological trait,root growth ,yield and germplasm of cotton under the field experiment.[Method]Based on the sun light,4 treatments were designed to inhance UV-B radiation of cotton,the normal dose of every treatment radiation were follows:0 kJ/m~2 (R0),0.5 kJ/m~2(R1),1.0 kJ/m~2 (R2) and 1.5 kJ/m~2 respectively.The effect of enhancing UV-B radiation on biological trait index such as leaves,plant height,stem diameter,leaf area and the index of root growth,yield and quality of cotton were investigated.[Result]Results show that with the extension of radiation time and radiation enhanced leaf visible injury became more serious,height and stem diameter of R1,R2 and R3 reached a significant difference(P<0.05),all differences of leaf area treated reached a significant level,dry weight per plant reached a best significant level(P<0.01); compared with the control,the root morphology changed dramatically,length of root of R1,R2 and R3 have been reduced compared with that of control;quality and yield of cotton was significantly lower than that of control.[Conclusion]The enhanced UV-B radiation made a close relation between aerial part and root part of cotton,the greater UV-B radiation,the geater effect on cotton.