The invention provides 
parecoxib sodium which is prepared by controlling an intermediate 
impurity and in particular provides a preparation method of a 
parecoxib sodium compound as well as the intermediate 
impurity and an application of the 
parecoxib sodium compound. According to the preparation method provided by the invention, 3-methyl-4,5-diphenyl-4,5-dihydro-
isoxazole-5-
alcohol is used as an isomer 
impurity for preparing 5-methyl-3,4-diphenyl-4,5-dihydro-
isoxazole-5-
alcohol as an intermediate of the 
parecoxib sodium, the quality of the 3-methyl-4,5-diphenyl-4,5-dihydro-
isoxazole-5-
alcohol is controlled in the preparation of the 
parecoxib sodium, specifically, the impurity content is required not to be higher than 0.5 percent, and an important significance is provided for the product quality of the 
parecoxib sodium; by obtaining the 3-methyl-4,5-diphenyl-4,5-dihydro-isoxazole-5-alcohol as an isomer impurity of the important 5-methyl-3,4-diphenyl-4,5-dihydro-isoxazole-5-alcohol and further studying 3-methyl-4,5-diphenyl-4,5-dihydro-isoxazole-5-alcohol in the aspects of preparation process, detection process and purification process, important 
quality monitoring significance is provided for the process with the 5-methyl-3,4-diphenyl-4,5-dihydro-isoxazole-5-alcohol as an industrial production 
raw material.