Inverse Compton scattering X/gamma-ray source can produce quasi-monochromatic, continuously tunable, high brightness, small spot size, polarization precisely controllable, and ultrashort (ps or sub-ps) X-ray pulse in the energy regime ranging from tens keV to several MeV or even higher. Recently a 0.2-4.8 MeV quasi-monochromatic compact gamma-ray source with high peak spectral density based on the inverse Compton scattering has been proposed in the Department of Engineering Physics, Tsinghua University. This type of compact gamma-ray source will be used for advanced X/gamma-ray imaging application based on the nuclear resonance fluorescence. In this paper, we will present the optimization of the design.