The crack initiation and propagation in Al2O3 seeded P/M Rene95 have been studied by SEM observation in-situ for tension loading stage of the P/M Rene95 sample. The results show that during SEM in-situ tension process, cracks initiate at ceramic inclusions. Generally, the cracks nucleate at the inclusion/matrix interface, and easily propagate along the interfaces and reach the matrix. At last, some inclusion particles may separate from the matrix and fall off.