A 2.5-2.7 GHz Power Amplifier (PA) with high efficiency and low harmonic distortion in InGaP/GaAs HBT technology is designed.Multiple LC tanks are introduced into the output matching network of the presented PA to suppress the high-order harmonic distortions and improve efficiency.The simulation results show that, the PA achieves a high gain of 37.6 dB and a saturated output power of 32 dBm with Power Added Efficiency (PAE) of 36% at the saturated situation.The second and the third harmonic are both less than -60 dBc.