Abstract: Disclosed are nucleic acid-calcium phosphate nanoparticle complexes and application thereof in biomineralization. Specifically, disclosed are a biological mineralizer and a preparation method thereof. The mineralizer contains a complex formed by nucleic acid and amorphous calcium phosphate nanoparticles. Further, disclosed is a collagen fiber product containing the biological mineralizer or treated with the biological mineralizer, such as a medical device for being implanted into a patient. Further, disclosed is use of the biological mineralizer or the collagen fiber product in treatment of bone-associated diseases or disorders or improvement of bone conditions of patients. Further, disclosed is a method of using the biological mineralizer to induce biomimetic mineralization of collagen fibers or a preparation method of a mineralized collagen fiber product.