A preparation method of black-bone chicken oligopeptides and a separation and identification method of active peptide fragments belong to the technical field of biological medicine. The preparation method particularly comprises the following steps: pretreating a black-bone chicken which is killed and has feather being stripped off by wringing, adding water, heating, and fat removal, adding Protamex for enzymatic hydrolysis, then performing procedures of centrifugation, ultrafiltration, concentration, spray drying, and the like to obtain the black-bone chicken oligopeptides. Detection shows that components in the black-bone chicken oligopeptides, which has a molecular weight of less than 1000 Da, account for more than 85%. The black-bone chicken oligopeptides have high DPPH free radical removing activity with an IC50 value of 4.52 mg/mL. Also, the black-bone chicken oligopeptides have strong ACE inhibition activity with an IC50 value of 2.86 mg/mL. A part of active peptide fragments are separated and identified by an RP-HPLC method and a Q-TOF2 method, wherein 2 antioxidation active peptide fragments are LWR and NM; and 5 blood pressure-reducing active peptide fragments are LER, GAGP, KPGV, LH, and NM.