Most of reports about the 660 nm red laser focus on continuous wave（CW）or Quasi-CW output in recent years.However,the output pulse with short duration and high peak power also has important applications in many fields.In this paper,the rate equation of intracavity frequency doubling Q-switched laser is analyzed.The Nd∶YAG crystal combined with electro-optic Q-switch is adopted to eradiate 1319 nm fundamental wave.By using the intracavity double-pass frequency doubling with KTP crystal（Type Ⅱ phasing matching,φ=0°，θ=59.8°）,the laser is obtained with a single-pulse energy of 56 mJ,pulse duration of 45 ns,peak power of 1.24 MW at 660 nm.It greatly broaden the application field in laser medical treatment etc,and lays the foundation for further development of high power and high energy 660 nm red laser.