In measuring laser performances of Nd:YAG crystals it is always found that there are different results (such as pulsed or CW laser efficiency, internal loss) for the same crystal rod at the same experimental conditions when the rod is rotated in the cavity. We consider that is caused by the inhomogeneity of the laser rod.The influence of optical homogeneity of Nd:YAG crystals on the laser output charaete-tistics was studied. Laser performances of crystal rods have been measured. It is pointed out that stable laser output can be obtained with optically homogeneous crystal rods.