In this paper, we give accurate estimation of eigenvalues and singular values of A + B,C*AC and AB, where A, B and C are quaternions matrices. These results improve and generalze the results in [4] and [5]. We also obtainsum (?),for k=1,…,n. Where A and B are self-conjugate quaternions matrices of order n, and λ1≥…≥λn,μ1≥μn,λ1,(A + B)≥…≥λn(A+B) be the eigenvalues of A,B and A + B, respectively. |