Nanoscale multiple-gate fin-typed field effect transistors (FinFETs) are promising candidates for next generation semiconductor devices. Impact of the discrete-dopant number and discrete-dopant position on device characteristics is crucial for nanoscale semiconductor devices. In this paper, we study the discrete-dopant-induced potential and threshold voltage fluctuations in 16nm triple-gate FinFET devices. Discrete dopants are statistically positioned into the three-dimensional channel region to examine associated carrier transportation characteristics, concurrently capturing "dopant concentration variation" and "dopant position fluctuation". It is found that the inhomogeneity of the potential induced by the discreteness of the channel dopants significantly disturbs device threshold voltage, and thus the device characteristics. This study provides an insight into the source of fluctuation and fluctuations induced by discrete dopants in ultra-small field effect transistors with vertical channel structures.