L1 0 -FePt based perpendicular exchange coupled composite (ECC) films with both weak FePt interparticle exchange coupling (IPEC) and strong hard/soft exchange coupling (HSEC) are virtually crucial to improve the signal-to-noise ratio and the writability of recording media concurrently. This article reports synthesis and magnetic property tunability of the L1 0 -FePt:Au/Fe ECC film with low IPEC between neighboring L1 0 -FePt particles and strong HSEC between the hard L1 0 -FePt:Au composite layer and the soft Fe layer. Moreover, the magnetic domain configuration study reveals the domain wall assisted magnetization reversal mechanism. The coupled Fe layer facilitates reverse nucleation and magnetization reversal in the L1 0 -FePt:Au composite layer, leading to remarkable reduce of the switching field while maintaining high thermal stability.