The high power all solid state intracavity optical parametric oscillator (IOPO) at 1.5 μm eye-safe wavelength band based on KTA and KTP crystals is demonstrated. Under the repetition rate of 18 kHz, the optimum signal output power of 13 W at 1.5 μm with a 5.46 ns pulse width, and idler beam of 3 W at 3.4 μm were obtained using laser diode-side-pumped Nd:YAG 1064 nm high power laser as the KTA-IOPO pumping source. In addition, the characteristic of KTA-IOPO was compared with that of the similar crystal KTP. These results show that the absorption of 3.4 μm wavelength band in KTA was negligible compared with KTP crystal, allowing high-power and high-frequencey-conversion operation with minimal thermally induced refractive distortion in the OPO crystal.