As technology continues to advance, research and applications for Internet of Things (IoT) technologies are growing. The focus of this paper is a downlink non-orthogonal multiple access (NOMA) IoT system where a base station (BS) allows the same frequency to provide efficient services to both near and remote users during signal transmission, but direct linking is not possible for transmission to remote users due to obstacles and other factors. technology for near-side users as a transmission relay. According to the non-linear properties of the energy harvesting (EH) circuits, a more realistic non-linear model for EH is utilized to investigate the system performance. To begin with, we calculate the outage probability for both users. The approximation approach then aids us in obtaining the approximated closed-form expression of outage probability, which we can use to characterize the influence of system parameter design on outage probability. The theoretical analyses' accuracy is confirmed and the system's performance is illustrated by the simulation results.