Complex natural zeolite, fly ash, coment and adherent were chosen as the initial components for preparing biological filter haydite of 5- 7 mm in diameter used in wastewater. The haydite preparation using orthogonal of experiment measured the bulk density, apparent density, specific surface area, crushing strength and wear rate. According to the principles for making aggregates and the results of the orthogonal design method obtained the optimal ratios of the components and reaction time. The results show that zeolite quantity 60%, coment-to- fly ash 6:4 , adherent quantity 4%, zeolite haydite natural drying time 2.8 h, curing in tap-water 28 d. The microstructures and characters of zeolite aggregates were observed by scanning electronic microscope.