We first measured the hydrate equilibrium of two real gases from the South China Sea in the pressure range of 1.85 MPa to 9.32 MPa. Then, three kinetic hydrate inhibitors (poly(N-vinyl) pyrrolidone, Inhibex501, and synthesized KHI-HY4) were tested from 275.15 K to 283.15 K and the pressure range from 2 MPa to10 MPa in the case of two real gases under 11.6 K to 14.0 K subcooling. The results show that the maximum subcooling temperature of three hydrate inhibitors increased with the increase of the pressure for the real gases, and hydrate formation induction time increased more than 1.5 times with the inhibitor concentration decreasing for HY4 or Inhibex501 for the real gases at a certain subcooling range. It was believed that each inhibitor has its optimal subcooling for usage in real gas. When the subcooling reached the optimal value, remarkable inhibitory performance could be displayed.