Carbon nanotubes have a significant application in nanotechnology as nanopipes conveying fluids. In this paper, a pressure control model for transport of liquid mercury through carbon nanotubes using classical molecular dynamics simulations in conjunction with an atomistic model is presented. Wetting of single-walled carbon nanotubes by mercury occurs above a threshold pressure of liquid mercury. The liquid mercury can be transported through carbon nanotubes with the continuous increase of its internal pressure. Also, we show that single-walled carbon nanotubes can transport liquid mercury discontinuously when a periodical pressure is applied on the liquid.