Abstract: In this paper,type Ⅰ/type Ⅱ angle detuning and type Ⅱ/type Ⅱ po larization mismatch third harmonic generation scheme consisting of two doublers and two triplers are used.The scheme has been used to drive ignition targets,with high tripling efficiency for shaping pulse.The effects of depolarized fundamental radiation on the tripling efficiency and how to increase the tripling efficiency are discussed by means of modeling computation.The results give reference to engineering design.