  As a sequel to our previous work\cite{Feng2020}, we propose in this paper a
quantization scheme for Dirac field in de Sitter spacetime. Our scheme is
covariant under both general transformations and Lorentz transformations. We
first present a Hamiltonian structure, then quantize the field following the
standard approach of constrained systems. For the free field, the
time-dependent quantized Hamiltonian is diagonalized by Bogliubov
transformation and the eigen-states at each instant are interpreted as the
observed particle states at that instant. The measurable energy-momentum of
observed particle/antiparticles are the same as obtained for Klein-Gordon
field. Moreover, the energy-momentum also satisfies geodesic equation, a
feature justifying its measurability. As in \cite{Feng2020}, though the
mathematics is carried out in terms of conformal coordinates for the sake of
convenience, the whole theory can be transformed into any other coordinates
based on general covariance. It is concluded that particle/antiparticle states,
such as vacuum states in particular are time-dependent and vacuum states at one
time evolves into non-vacuum states at later times. Formalism of perturbational
calculation is provided with an extended Dirac picture.
