This paper is concerned with upper semicontinuity of pullback attractors, for a nonautonomous nonclassical diffusion equation with critical nonlinearity. In particular, under some proper assumptions, we prove that, the pullback attractor {Aε(t)}t∈R of equation (1.1) with ε∈[0,1] satisfies that for any [a,b]⊂R and ε0∈[0,1], distH01(Aε(t),Aε0(t))=0 and ∪t∈[a,b]∪ε∈[0,1]Aε(t) is precompact in H01(Ω).