The invention relates to a method for removing chemical oxygen demand (COD) in polyvinyl chloride wastewater. In the method, a wastewater tank, a wastewater delivery pump, a cooling tower, a reagent-dissolving barrel, a dosing pump, an air compressor, a pneumatic continuous biofilter and a reuse water tank which are connected in turn are utilized. The polyvinyl chloride wastewater generated in the suspension method production process of polyvinyl chloride is discharged into the wastewater tank, a part of polyvinyl chloride resin particles are precipitated in the wastewater tank through a precipitation method, then the wastewater is conveyed from the wastewater tank to the cooling tower by virtue of the wastewater delivery pump for cooling, finally the wastewater enters the pneumatic continuous biofilter, oxygen is supplied into the filter by virtue of the air compressor, the COD in the wastewater is removed through a biodegradation method, the reagent for biodegradation is supplied by the reagent-dissolving barrel, and the effluent is discharged into the reuse water tank to be recycled after the biological treatment. The devices utilized in the method are fewer; and the process is simple, reasonable and practical and can be widely used in the treatment procedure of the polyvinyl chloride wastewater and be especially used for removing the COD in the suspension method polyvinyl chloride wastewater.