Accompanied by the structural phase transition, the electron transport properties of single-walled carbon nanotubes bundles undergo a metal-semiconductor transition at a hydrostatic pressure of 1.5 GPa. In the semiconducting phase there coexist two effects——electron phase coherence which leads to two-dimensional electron weak localization, and Coulomb correlation which leads to the environmental quantum fluctuation of charge transport. We applied hydrostatic pressure up to 10 GPa to single-walled carbon nanotube bundles, and studied the bias voltage dependence of the differential conductance at low temperatures and in strong magnetic fields. Our results show that phase coherence and Coulomb correlation are two effects that independently influence on the electron transport process in the semiconducting phase of the single walled carbon nanotube bundles.