With the deregulation of electric power market and the growing size of large inter-connected power systems，the need of performing fast online multi-area available transfer capability（ATC）evaluation has emerged.This paper is concerned with a multi-area ATC evaluation method based on Kron reduction and operating in four steps，namely，system decomposition，regional equivalence，data exchange and topology update.The implementation of system decomposition enables minimum exchange of information among different control areas and the central coordinator，and the massive calculation pressure of multi-area ATC is shared.An enhanced DC-ATC model is adopted to boost speed while keeping the error under control.The method is validated through an IEEE 118-bus test case.