Abstract
This paper concerns the abstract Cauchy problem of fractional evolution equations with almost sectorial operators. The suitable mild solutions of evolution equations with Riemann-Liouville derivative and Caputo derivative are introduced respectively. The existence theorems of mild solutions of Cauchy problems are established. The results obtained here improve and generalize some known results. Finally, an example is given for demonstration. (C) 2014 Elsevier Inc. All rights reserved.