Abstract: The limitations of various typical flux-Limited diffusion theory and advantage of asymptotic diffusion theory with time absorption constant are analyzed and numerically compared. The conclusions are as follows. Though the flux-Limited problem in neutron diffusion theory are theoretically solved by means of derived flux-Limited diffusion equation, but it's going too far to limit flux due to the inappropriate of the assumption in deriving flux-limited diffusion equation. The asymptotic diffusion theory with time absorption constant has eliminated the above-mentioned limitation, so it is more accurate than flux-Limited diffusion theory in describing neutron transport problem.