The invention provides a preparing method for a deep oxidation catalyst of coal gasification waste water. The preparing method comprises the following steps that firstly, metal salt is mixed according to a certain proportion, then dissolved into a solvent and prepared into a mixed solution with the mass fraction of 1-15%, and the mixed solution is stirred and placed for 6-12 min at the room temperature; secondly, a carrier is steeped into a prepared acid solution with the mass fraction of 2-10%, subjected to ultrasonic treatment for 5-60 min, washed with pure water until pH ranges from 6 to 7, and dried in an oven for standby use; thirdly, the mixed solution prepared in the firstly step and the carrier treated in the second step are mixed according to the mass ratio of (0.8-1.2):(0.8-1.2), subjected to standing for 1-24 h, dried in the oven and then roasted at high temperature; preferably, the mass ratio is 1:1. Under the action of the catalyst, organic pollutants can be greatly reduced as long as air is introduced into the waste water, and the catalyst is low in cost and good in regenerability.