Essential fatty acids are those that could not be synthesized by the body itself but crucial for health and life. Studies have shown that ω-3 fatty acids may facilitate human physiological functions. Mammals lack ω-3 desaturase gene, and the Δ15 fatty acid desaturase (Δ15 Des) from Caenorhabditis elegans can transform the ω-6 polyunsaturated fatty acids (PUFAs) into ω-3 PUFAs. Transgenic mice expressing Δ15 Des enzyme activity was constructed by using a PiggyBac transposon (PB). Homozygous transgenic mice with stable inheritance was bred in a short time, with a positive rate of 35.1% achieved. The mice were fed with 6% ω-6 PUFAs and the changes of fatty acids in mice were detected by gas chromatography (GC). The expression level of Δ15 Des in mice was detected by quantitative PCR (qPCR) and Western blotting (WB). qPCR and GC analysis revealed that the percentage of positive mice harboring the active gene was 61.53%. Compared with traditional methods, the transformation efficiency and activity of Δ15 Des were significantly improved, and homozygotes showed higher activity than that of heterozygotes. This further verified the efficient transduction efficiency of the PiggyBac transposon system.