A high beam quality diode-pumped Nd:YAG master oscillator power-amplifier (MOPA) laser with three end-pumped slab amplifiers is developed. The Q-swtiched side-pumped rod oscillator presented a pulse energy 3.1 mJ with beam quality factors of M x2=1.17 and M y2=1.15 at a repetition of 1 kHz. The MOPA system delivered a pulse energy of 1.36 J with a pulse width of 48.2 ns and an extraction efficiency of 44.8%. The beam quality factors of M x2=1.72 and M y2=3.85 are measured without any phase-conjugators or adaptive optics.