The invention relates to a liquidoid air oxidation method for preparing 3, 3', 4, 4'-benzophenone tetrabasic carboxylic acid and a preparation method for 3, 3', 4, 4'-benzophenone tetrabasic carboxylic acid. The invention can solve the problems of the prior art such as adoption of toxic purification solvent, difficulty in feeding, low purity and low yield during the process of preparing 3, 3', 4, 4'-benzophenone tetrabasic carboxylic acid. The procedures are as follows: the 3, 3', 4, 4'-tetramethyl hexichol ethane, glacial acetic acid, tetrahydrate cobalt acetate, tetrahydrate manganese acetate and tetrabromoethane are mixed and dissolved according to the mol ratio, and then is arranged into a reaction kettle so as to react under the conditions of pressurizing, heating and stirring, and then the 3, 3', 4, 4'-benzophenone tetrabasic carboxylic acid is obtained through pressure relief, discharge, cooling and centrifugation. The invention has the advantages that: the preparation process of the invention is a weight increment reaction, thereby the yield of the product reaches 100 percent to 140 percent, and the purity of the product can reach 97.5 percent to 99.8 percent.