Supercritical water is widely used in a variety of chemical processes such as hydrothermal synthesis, hydrolysis reaction and environmental friendly treatment of wastes. And it is widely accepted that many anomalous properties of water as a solvent arise as a consequence of specific hydrogen bonding interactions of its molecules. Despite of the importance, direct experimental investigation of water molecules at high temperature, high pressure and nano-scale confinement represents a very challenging task. In this work we report the study of the temperature (up to 800K) and pressure (up to 1000MPa) effects on structural properties of water molecules confined in different carbon nanotubes (CNTs) by molecular dynamics (MD) simulations. It was found that the temperature and pressure greatly affect the number and lifetime of hydrogen bonds of the confined water molecules in CNTs. And on the other hand, the simulation results showed that because of helicity difference between (6, 6) and (10, 0) CNTs, the density profile of supercritical water is different in the two type of CNTs.