The Hawking radiation of Dirac particles in a charged Vaidya-de Sitter blac
k hole is investigated by using the method of generalized tortoise coordina
te transformation. It is shown that the Hawking radiation of Dirac particle
s does not exist for P-2, Q(1) components, but for P-2, Q(1) components it
does. Both the location and the temperature of the event horizon change wit
h time. The thermal radiation spectrum of Dirac particles is the same as th
at of Klein-Gordon particles.