Passive Q-switched laser has been achieved in Nd:YAG transversely pumped by a Q-CW 60 W laser-diode-array. While the laser diode was working on a repetition rate of 10 Hz at power as high as 60 W and pulse width of 400 μs, a free running stable oscillation with output energy of 3 mJ was obtained. Making use of a LiF:F2-crystal as a saturable absorber, Q-switching operation was succeeded. There were three multiple-transverse-mode pulses with energy of 400 μJ and width of 11.5 ns for every individual pulse within per period. Some suggestions are presented here in order to obtain highly efficient single pulse with single-transverse-mode.