A diode-pumped Nd:YAG 1.319 μm ΤΕΜ00 laser with high power is presented. Through optimizing the stable resonator and inserting a diaphragm to get large fundamental mode volume and reduce the rod thermal lensing, when pumping power is 343 W, an output of 6 W TEM00 1.319 μm laser with an optical-to-optical efficiency of 1.74% and beam quality M2<2 has been demonstrated.