The interfacial area transport equation(IATE) is being investigated to replace the flow regime map in the one-dimensional two-fluid model (1-D TFM). The partition of two-phase wall drag is a part of flow regime-dependent constitutive relations in the code using the 1-D TFM such as RELAP5. Hence, to develop the partition method for two-phase wall drag that is consistent with 1-D TFM using the IATE, the mechanism for the partition was investigated and clarified in this work. And the partition method for two-phase wall drag that can capture the dynamic change of two-phase flow structure was developed with the clarified mechanism. Furthermore, the method was preliminarily validated with the experimental data, which shows that the two-phase wall drag computed by the method can accurately capture the variation of flow structure and relative velocity in transient two-phase flow. Accordingly, the developed method is able to take advantage of the IATE.