The invention provides a salmon small molecule polydeoxyribonucleotide (SMPDRN) product with a molecular weight concentrated in an efficacy range of the salmon small molecule polydeoxyribonucleotide product, a controllable precise preparation method of the salmon small molecule polydeoxyribonucleotide product, and application of the salmon small molecule polydeoxyribonucleotide product to the fields of cosmetics, medicine, nutritious food and health food. The molecular weight of small molecule polydeoxyribonucleotide is 50-1000 bp, and the mass of the molecular weight of the small molecule polydeoxyribonucleotide at the 50-500 bp fragment accounts for more than 85% of the total mass of the small molecule polydeoxyribonucleotide; and the molecular weight of the SMPDRN is concentrated in thehigh-efficacy range, the pertinence is higher, the efficacy is more stable, and the obtained product has significant effects in improving cell activity, promoting collagen synthesis, regenerating damaged skin, promoting wound healing, tightening skin, increasing skin elasticity, eliminating wrinkles, delaying skin aging, resisting oxidation, preventing formation of color spots, resisting inflammation, repairing damaged cells and other aspects by being verified by cell, animal and human experiment, and is better than an existing PDRN product.