  SHINE, as the first hard x-ray free-electron-laser (FEL) facility in China,
is designed to provide high-brightness FEL lasing under high-repetition-rate
operation mode. In order to drive x-ray FEL pulses with high qualities, the
photoinjector section is deployed to provide the specified electron beam with
low transverse emittance and high brightness. Normally the multi-objective
optimization algorithm is employed in the injector beam dynamics design. In
this paper, the many-objective optimization algorithm NSGA-III is introduced to
the injector physical design for optimizing the 4 beam quality properties for
the first time. The results of the optimization are presented and analyzed. The
application of NSGA-III can provide guidance for further physical research as
well as improve the beam dynamics optimization efficiency.
