Abstract: Internal force and deformation of vertical cables in unidirectional or bidirectional single-layer plane cable net curtain wall structural system are always rather complex. Its analytic analysis is therefore an important theoretical basis for the analysis of the whole structure, but, corresponding research on this subject is very limited. This paper treats it as an equivalent pretensioned vertical cable under bidirectional uniform load, and tries to find an analytic method. According to the load and deformation characteristics, an analysis scheme are firstly brought forward, which includes three phases. And, for the latter two phases which are more important, the paper establishes equilibrium equations and deformation compatibility equations considering the axial load effects. By solving the equilibrium equations, the vertical displacement equation and horizontal deflection equation of vertical cables are obtained, and the formula that reflects the variation of extreme deflection position and axial load effects is found. This paper also gives the deflection equation at the third stage, which is expressed as two polynomial approximations respectively, and moreover, the simplified form and iteration solution. Calculation examples show that the analytic method has good agreement with finite element method, indicating that the analysis scheme and results are correct and the approximated deflection equations have good accuracy.