In this paper, we investigate opportunistic secure multiuserscheduling in energy harvesting untrusted relay networks,where an energy-constrained amplify-and-forward (AF) relay harvestsenergy from the received radio frequency signal via usingthe power splitting protocol. To exploit the potential advantages(e.g., multiuser diversity and direct links) for secrecy improvement,we examine three opportunistic user scheduling schemes,i.e., optimal scheduling scheme, maximum scheduling scheme, andminimum scheduling scheme. Specifically, the optimal schedulingscheme performs user selection by maximizing the ratio betweenthe signal-to-noise-ratio (SNR) at the destination and the correspondingSNR at the untrusted relay. The maximum schedulingscheme is conventional user selection that maximizes the channelgain of the direct links. For the minimum scheduling scheme, wetry to reduce the overheard information at the untrusted relay byselecting the user with the lowest channel gain of the relay links. For these three schemes, we comprehensively examine the achievablesecrecy performance including probability of positive secrecyrate, secrecy outage probability (SOP), asymptotic SOP, secrecythroughput (ST), as well as secure energy efficiency (SEE) to helpfacilitate an energy-efficient secure transmission design. Simulationresults demonstrate that the maximum scheduling scheme outperformsthe minimum scheduling scheme in terms of SOP at relativelylow SNRs and target secrecy rates.