A laser-diode array side-pumped Nd∶YAP intra-cavity frequency-tripled 447 nm pulse blue laser was reported. After high peak power of polarized 1 341.4 nm fundamental laser was generated by using high frequency laser-diode array side-pump Nd∶YAP crystal, V-type resonator and LN crystal for Q-switched, 670.7 nm red laser second harmonic generation(SHG) was obtained with Ⅱcritical phase matching(CPM) KTP ctystal, and 447.1 nm blue laser by sum frequency mixing(SFM) of the 1 341.4 nm and 670.7 nm radiation was obtained withⅠCMP LBO ctystal. The experimental results show that a optimited V-type resonator can increase the efficiency of nonlinear conversion. At the incident pumping power of 92.4 W, the output power of polarized blue laser is 887 mW, the peak power of blue laser is 17.7 kW, and the pulse width is 50 ns, corresponding to an optical-to-optical conversion efficiency of 0.96%.