The gain and refractive index combination guiding is investigated by simulating a dual-end pumped rod Nd:YVO<sub>4</sub>
amplifier. From the simulation, it is indicated that the large transverse gain gradient and the gain coefficient are
contribute to the gain guiding to enhance the beam quality. The appropriate spherical aberration in the input beam is
helpful for improving the beam quality of output beam. Moreover, the gain saturation determines which one could
dramatically influence beam quality between the gain guiding and the refractive index guiding.