Question

which phycisal parameter remain constant during refraction

Answer 1

 Ignoring the reflected portion of the wave, the amplitude of the EM fields stay the same, but since the area occupied by the wave changes upon refraction, the irradiance changes. If you consider the special case of normal incidence at rest, polarization, frequency, and irradiance are preserved (ignoring the reflected wave.).

Answer 2

Assuming the media are at rest, the frequency does not change.Ignoring the reflected portion of the wave (or if you prefer, the probability wave function of the photon), the polarization does not change, provided both media are isotropic. (No birefringence present.)