Provided are an anti-PD-L1/anti-PD-1 natural antibody structure-like heterodimeric bispecific antibody and a preparation thereof. In particular, provided are a highly stable heterodimeric anti-PD-L1/anti-PD-1 bispecific antibody with characteristics of a natural IgG and without mismatched heavy chain-light chain, and a preparation thereof. The bispecific antibody can bind to both target molecules and is more effective in treating a complex disease.