Abstract: A 76 mm-diameter by 100 mm-long BGO scintillation detector is assembled to detect the highenergy gamma-rays produced from intermediate energetic heavy-ion nuclear reaction. The energyresponse of the detector is studied in the incident gamma-rays energy range of 0.661 MeV to17.65 MeV, the monoenergetic gamma-rays are generated by radiative sources and several lowenergy (p, γ) resonant nuclear reactions. The response function is obtained by delicate datefitting. The full energy peak energy resolution is 14.2% at 0.661 MeV and 4.1% at 17.65MeV, respectively. One analyzing method of the energy spectra of high energy gamma-rays is al-so discussed in the paper.