[en] The solenoid magnet design for a 20 MeV flash X-radiography is presented. Prototype solenoid magnets have been demonstrated that it has a magnetic axis tilt less than 1 mrad and magnetic axis offset 0.2 mm, respectively. The design features of the solenoid magnets, which are slender majority of transverse magnetic field and high precision of magnetic alignment, have been proved to meet the 20 MeV linear induction accelerator performance goals by the experiments of the 2 MeV injector