Within the framework of the perturbative QCD approach, we calculate the time-like B_cB_c(B_c^*) form factors F(Q^2) and A_2(Q^2). We include relativistic corrections and QCD corrections, either of which can give about 20% correction to the leading-order contribution, but there are cancellation effects between them. We calculate the cross sections of the e^+e^-→ B_c^-B_c^+(B_c^*+) processes. The cross sections are enhanced at the Z pole to be σ^PP(Q=m_Z) ∼ 1.3×10^-5pb and σ^PV(Q=m_Z) ∼

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... b, which are still too small to be detected by proposed e^+e^- colliders such as the Circular Electron Positron Collider.