Abstract: This paper describes the design considerations of the DragonI linear induction accelerator (LIA) at Institute of Fluid Physics, China Academy of Engineering Physics. The DragonI facility is an electronic linac and consists of a -2.0MV/+1.5MV bipolarity inductive adder injector, 72 accelerating cavities, pulsedpower system, beamtransport, control and auxiliary systems. It can produce an electron beam of 3kA, 20MeV with pulse width of 90ns (FWHM). Good accelerating voltage pulse for each cavity with width of 120ns (FWHM) and up to 60ns flattop within ±1% variation has been obtained for high beam quality.