In this correspondence, we study the outage performance for the simultaneous wireless information and power transfer (SWIPT) full-duplex relay system. The energy-constrained relay node is subject to the co-channel interference (CCI). Although the interference deteriorates the system performance, it can also provide additional energy for harvesting at the relay. Hence, in order to quantify the impact of CCI for the energy harvesting system, a closed-form and asymptotic expression of the system outage performance is derived for the power splitting (PS) based relay. Moreover, with the aid of the approximated outage analysis, we obtain a simple expression for the optimal PS ratio. Simulation results are provided to validate the accuracy of our analysis.