Triboelectrification typically occurs in the friction process. In this study, we investigated the effect of liquid lubricants of various polarities on triboelectrification in a friction pair consisting of a steel ball and polyvinylidene fluoride blocks. The results revealed that alkanes and alkenes enhanced triboelectrification. On addition of PAO 4, the friction coefficient reduced considerably, and the short-circuit current could be output stably for a long time. With the increase in the viscosity of PAO, the triboelectric signal gradually decreased. This study revealed that the appropriate lubricant and the quantity of liquid can increase the size of the triboelectric signal to achieve a stable output for a long time.