The invention discloses a modified filling for a waste gas bio-trickling filter and a preparation method of the modified filling. The preparation method comprises the steps of after washing ceramic particles with the particle sizes of 5mm-100mm with water, steeping the ceramic particles in hydrochloric acid, taking out the ceramic particles, washing the ceramic particles with water, steeping the ceramic particles in an NaOH solution, taking out the ceramic particles, washing the ceramic particles to be neutral with water, drying, steeping with a modifier, draining off, and drying, so as to obtain the modified filling for the waste gas bio-trickling filter. The modified filling for the waste gas bio-trickling filter and the preparation method are particularly applicable to bio-trickling filter devices, the absorption effect of the obtained modified filling to degrading bacteria is good, the waste gas treatment efficiency of the bio-trickling filter can be effectively improved, meanwhile, the raw material cost is low, the processing process is simple, and the market application prospect is wide.