A curtain cutting aid includes a curtain holder including two hollow holder blocks arranged in parallel and defining therein a respective insertion space in communication with each other for a insertion of a curtain, a bearing plate connected between the two hollow holder blocks and a cutting groove defining between the two hollow holder blocks for the insertion of a cutter to cut off the inserted curtain, and a stop rod selectively and detachably mounted in the insertion space of one of the two hollow holder blocks to stop the inserted curtain in place for cutting. Thus, the curtain cutting aid can effectively enhance the convenience and precision of the cutting operation.