In K2ZnBr4 crystal, the monoclinic phase with the Sr2GeS4-type structure (P2(1)/m, Z=2) is transformed into the orthorhombic phase with the beta-K2SO4-type structure (Pmcn , Z=4) above 470K (an alpha-beta transition). This alpha-beta transition is known to be a reconstructive one. The crystal structure of the orthorhombic phase is refined in order to investigate in detail the structural change on the phase transition. It is found that the structure of the surroundings of one of two independent K+'s in the monoclinic phase is almost the same as the rotated structure of the surroundings of one of two independent K+'s in the orthorhombic one. We also discuss the difference between the crystal structures of K2ZnCl4 (orthorhombic) and K2ZnI4 (monoclinic) and the corresponding structures of K2ZnBr4.