The invention relates to the technical field of genetic engineering and particularly discloses a recombinant yarrowia lipolytica bacterial strain as well as a construction method and an application thereof. A genome of the recombinant yarrowia lipolytica bacterial strain comprises a nucleotide sequence as shown in any one of SEQ ID NO: 1-3. The construction method comprises the following steps of constructing a key gene dhcr7 in a biosynthesis way of campesterol expressed by a single-gene expression cassette through an OE-PCR (overlap extension-polymerase chain reaction) method; cutting down the single-gene expression cassette through restriction enzyme, transferring the single-gene expression cassette into yeast at one time to perform homologous recombination among fragments and integration of a special erg5 lotus of the genome, screening a completely-assembled converter through an auxotrophic culture medium and genome PCR to obtain a novel recombinant yarrowia lipolytica bacterial strain. The novel recombinant yarrowia lipolytica bacterial strain can be applied to biosynthesis of campesterol, and a relatively high yield can be kept.