The polarization emission spectrum and the angular dependence of polarization ratio of the blue emission from KCl:Eu²⁺ were investigated at 78.8 K. The polarized emission at 420 nm consisted of several components. The angular dependence of polarization ratio of each component is proportional to sin(2 ) or -cos(2 ), when the exciting light is polarized at with respect to the z -axis for the [100]-[010] optical arrangement. The relaxed excited states (RESs) of Eu²⁺ responsible for the 420 nm emission are presented in terms of the adiabatic potential energy surface (APES), taking into account the Jahn-Teller effect (JTE) coupling to the E_g mode and the spin-orbit (SO) interaction. The charge-compensating cation vacancy (CCV, V_c ^- ) also causes an additive perturbation.