Precise determination of the branching ratio provides an advantageous opportunity for understanding the electroweak structure of the Standard Model, measuring the CKM matrix element , and probing new physics models. In this paper, we discuss the potential of measuring the process with decaying leptonically at the proposed Circular Electron Positron Collider (CEPC). We conclude that during the Z pole operation, the channel signal can achieve five- significance with Z decays, and the signal strength accuracies for can reach around 1% level at the nominal CEPC Z pole statistics of one trillion Z decays, assuming the total yield is . Our theoretical analysis indicates the accuracy could provide a strong constraint on the general effective Hamiltonian for the transition. If the total yield can be determined to (1%) level of accuracy in the future, these results also imply could be measured up to (1%) level of accuracy.