A new method, which correlates rate constants of chemical reactions and density or pressure in supercritical fluids, was developed. Based on the transition state theory and thermodynamic principles, the rate constant can be reasonably correlated with the density of the supercritical fluid, and a correlation equation was obtained. Coupled with the equation of state (EOS) of a supercritical solvent, the effect of pressure on reaction rate constant could be represented. Two typical systems were used to test this method. The result indicates that this method is suitable for dilute supercritical fluid solutions.