A red laser at 670.7 nm is obtained with high-power continuous-wave laser diode array (LDA) off-axis stagger side-pumped Nd:YAP laser crystal and type-I critical phase matching of LBO crystal. The prefect matching of gain field inside the crystal and fundamental mode of cavity can be made by this structure, then high beam quality, high power output can be easily obtained. By using a short folded-cavity resonator, the thermal focal length of Nd:YAP crystal is measured, and the parameters of laser cavity are selected by computer optimum design. With incident pump power of 800 W for the Nd:YAP crystal, the red laser output of 8.3 W at 670.7 nm is obtained, the beam quality M2 value equals 5.6 in both horizontal and vertical directions at the maximum output power, and the power stability is better than 3% at the maximum output power during 30 min. The experimental results show that the intracavity frequency-doubled by the pump structure is an effective method for high power red laser.