The defects of alexandrite crystal (BeAl2O4: Cr) grown by Chochralski technique were investigated by chemical etching, optical microscopy, X-ray diffraction topography and electron microprobe analysis. The results obtained are summarized as follows: (1) Eolicdle dislocation etchants were restablished on the (1 0 0), (0 1 0) and (0 0 1) surfaces. (2) The distributions of dislocations in crystals are nonuniform. There are two sources for the dislocation production. One is seed and other is inclusions. Most of the dislocations are edge ones, their Burger's vectors are in <1 0 0> direction and glide planes are (0 1 0). (3) The main inclusions such as bubbles, tunnels and secondary phase pricipitate particles often appear in grown crystals, which are caused by impurities in raw material and constitutional supercooling during growth.