Abstract: In order to improve the output power and the optical-optical conversion efficiency of a laser diode pumped all-solid-state laser,a double Nd:YVO4 crystals green laser was designed.Through investigation of temperature field distribution in laser crystal and based on the transmission matrixes,the stable condition of cavity influenced by the thermal lens effects of double laser crystals was analyzed and a folded cavity of double-end-pumped double Nd:YVO4 crystals was introduced.In double-ends-pumped double Nd:YVO4 crystals green laser system,Ⅰ-type noncritical phase matching LBO crystal was used as intracavity doubling frequency.When the pump power of two diode lasers was 26.56W,the 5.5W CW 532nm green laser was got and the optical-optical conversion efficiency reached up to 20.7%.The result shows that the double laser gain mediums inserted in cavity can not only improve the optical-optical conversion efficiency of laser,but also enhance the resonant stability through the interaction of two laser crystals' thermal lens effect.