This paper investigates modeling approaches of circular concrete-filled steel tube (CFT) column under cyclic load based on flexibility and fiber model. The effects of model parameters on modeling results is discussed, including constitutive relationship of materials, division of the fiber section, and the number of integration points. The results show that the material constitutive relationships of concrete and steel are prime important to the accuracy of the computational results. Three to five integration points for one CFT column in the flexibility-based analysis can achieve the desired accuracy and computational efficiency. The computational result is not sensitive to the number of sectional fibers. However, the desired accuracy can not be obtained if the number of the sectional fiber is not enough.