This paper analyzes the problems and contradictions that occur when the traditional special theory of relativity which uses the speed of light in a vacuum as an invariant constant, studies the propagation of light in media. These problems are re-examined and discussed with the special theory of relativity of variable speed of light. The transformation relationship of the characteristic quantities describing light wave frequency ν, phase velocity w and the direction angle α of the wave normal between the two inertial coordinate systems in vacuum S and in medium S' were derived; combining the transformation of the light ray speed u which describes light granular motion, the de Broglie wave-particle velocity relationship in the vacuum u w = c2 is νextended to the medium to become u' w' = c'2. Corrected the approach of the traditional special theory of relativity when dealing with these problems, in which the transformation from the space-time coordinates to the relevant physical quantity is limited to the half-sided transformation of the media into the vacuum (not two sided transformation), so that the resulting contradictions and problems are all solved. Optical experiments that support the traditional special theory of relativity, such as the Fizeau experiment and the Michelson-Morley experiment, not only still support and agree with the generalized special theory of relativity with variable speed of light, but also obtain a more correct and satisfactory interpretation from it.