Vapor-liquid phase equilibrium data including composition, densities, molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2 K to 353.2 K were measured in a variable-volume visual cell. The properties of critical point were obtained by extrapolation. The results showed that critical temperature, critical pressure and critical compressibility factor of CO2-isobutanol system decreased with the increase of critical CO2 content. The phase equilibrium Model was established by Peng-Robinson equation of state and van der Waals-2 mixing regulation, and model parameters were determined by optimization calculation of nonlinear least square method. The correlation between calculated values and the experimental data showed good agreement.