A method is developed to reduce the problem of steady relativistic gasdynamics to an equivalent Newtonian flow. The basic theorems, and laws of the steady relativistic gases are established. Numerical studies of the flow fields of a relativistic shock wave, nozzle flow, and Prandtl‐Meyer flow are also presented. The aspects of photon gasdynamics and the basic experiments for the justification of the relativistic photon gas theory are suggested.