Abstract: The structure of the 3-mirror folded resonator was optimized for Laser-diode end-pumped Nd∶YVO4/KTP intracavity frequency-doubled laser. The influence of parameters including the resonator length, curvature radii of mirrors, Nd∶YVO4 and KTP thermal effect on the stable area of the laser resonator and the basic mode size of Nd∶YVO4 crystal was investigated. The research shows that the experiment result is consistent with that of the theoretical analysis. The red laser output powers at different folded angles of the folded resonator were compared, the effective frequency-doubled efficiency of 10.8% was obtained at the optimal folded angle 25°. The experimental result was explained theoretically with the relation between the polarization property of the fundamental laser beam and the phase matching of KTP.