We demonstrate a three-nanosecond equidistant sub-pulse multi-step Q-switched Nd:Y₃Al₅O₁₂ (Nd:YAG) laser. In the time interval of 100–1000 ns, three pulses with the same nanosecond interval and the same peak power are obtained at the pulse width of 24 ns, 28 ns, and 36.6 ns, respectively. The energy is 32.5 mJ, and the optical efficiency is 10.8%. The multi-step Q-switched method does not require the insertion of other optical elements into the traditional Q-switched laser, and it is very suitable to obtain pulse group output with several nanosecond pulse intervals.