The invention relates to a construction method of a homologous repair vector based on a CRISPR/Cas9 system, and belongs to the technical field of genetic engineering. The construction method comprisesthe following steps: with a plasmid PCBC and wild-type arabidopsis genome as templates, amplifying a target band AS-gRNA containing a target sequence and an AS homologous repair template segment by virtue of PCR, implementing electrophoresis and gel cutting, and recovering the target band; implementing enzyme digestion on a plasmid PHDE-mCH by virtue of Bsa1; assembling and linking a PHDE-mCh vector, which undergoes complete enzyme digestion, with the ASgRNA by virtue of homologous recombinase, so that a recombinant plasmid PHDE-ASgRNA is formed, implementing transformation and sequencing identification, then linking the PHDE-ASgRNA plasmid, which is correct in sequencing and is subjected to enzyme digestion by virtue of EcoR1, with AS homologous repair template segment homologous recombinase, and implementing transformation and sequencing identification, so that the PHDE-ASgRNA-AS homologous repair vector is constructed. According to the technique provided by the invention, the method for constructing the CRISPR/Cas9 system which has a site-specific editing function on target biology genome is actually implemented; the vector is constructed just by conducting PCR by one step, sothat the method is simple and easy to implement; and the method, which is unnecessary to purify or recover a digestion vector and a PCR product, is high in assembly efficiency.