In order to improve the calculation method of creak width of concrete beams strengthened with CFRP sheet,based on the theory of bond-slippage,the calculation formulas for the crack spacing and width of concrete beam strengthened with CFRP sheet are derived,and theoretical calculation method for the crack width is presented,which is suitable for concrete and prestressed concrete beams strengthened with CFRP sheet.On the other hand,following the traditional idea of crack width of reinforced concrete structures,the influence coefficients considering the CFRP sheet and the bonded prestressing steel are introduced in the calculation formula of the average crack width l m.The influence coefficient δ f considering the CFRP sheet and the bonded prestressing steel is introduced in the calculation formula of crack width w m and the calculation formula of coefficient of uneven stress of steel bar ψ,and the corresponding semi-theoretical-semi-empirical formula is given.The calculation results in above two methods are in good agreement with the test results.