In this paper,we consider the existence and uniqueness of the mild solutions for a class of fractional non-autonomous evolution equations with delay and Caputo's fractional derivatives.By using the measure of noncompactness,β-resolvent family,fixed point theorems and Banach contraction mapping principle,we im-prove and generalizes some related results on this topic.At last,we give an example to illustrate the application of the main results of this paper.