Composite multi-connected gRNA and RNAi expression cassette for vector expression

The invention provides a composite multi-connected gRNA and RNAi expression cassette for vector expression. The composite multi-connected gRNA and RNAi expression cassette can be applied to a eukaryotic expression vector system. The composite multi-connected expression cassette comprises a promoter for promoting transcription, one or more gRNA expression cassette bodies, one or more RNAi expression cassette bodies and a terminator for terminating transcription; the expression cassette has the function of modifying target genes at the DNA level and the mRNA level, and the gRNA/CRISPER gene modifying expression cassette bodies are connected with the RNAi expression cassette bodies through intervening sequences in an alternative series connection mode. The composite multi-connected gRNA and RNAi expression cassette for vector expression solves the problem that in an existing expression structure, one promoter can only be connected with one gRNA and one transcription terminator.