The invention belongs to the field of ceramic near-net forming, and discloses a method for preparing mullite ceramics by a high valence counter ion solidification injection molding process. The methodcomprises the following steps of (a) selecting coal series kaolin, ammonium hydroxide and water as raw materials; performing primary ball milling and uniform mixing on the coal series kaolin, the ammonium hydroxide and the water to form water-based slurry; adding iodate curing agents into the water-based slurry; performing secondary ball milling and uniform mixing to obtain cured water-based slurry; adding ester PH regulators into the cured water-based slurry; performing vacuum stirring degassing to obtain the required ceramic slurry; (b) injecting the ceramic slurry into a nonporous mold; then, performing water bath treatment on the nonporous mold; next, performing demolding and vacuum drying to obtain dry blank; after the dry blank is sintered, obtaining the required mullite ceramic sintering body. The method provided by the invention has the advantages that green and environment-friendly effects are achieved; the cost is low; the curing time is short; the curing temperature is low;the blank uniformity is high; the operation is simple; the molding efficiency is high, and the like.