According to the load-bearing characteristics of flexible materials, a universal design method for inflatable wings is proposed based on the design conception of approaching the general airfoil to its serial inscribed circles, which is applicable to both symmetric and asymmetric airfoils. Taking the non-symmetrical airfoil Eppler 398 for example, the design process is illustrated through the combination of programming and graphics. An inflatable wing model manufactured on the basis of this design method accords very well with the blueprint, which shows that the design conception is correct. A bending stiffness experiment is carried out upon the inflatable wing model, the experimental results indicate that this kind of inflatable wing is good in bending stiffness and can be used to replace rigid wings as long as the internal pressure is large enough, thus the feasibility of the design method is verified.