Abstract: The front-end readout ASIC of a PET with SPM detectors is designed based on TSMC 0.18um CMOS process.The designed chip consists of both the energy and time measurement chain,including RGC pre-amplifier,integrator,shaper,sample and hold circuit,discriminator,monostable circuit and so on.The Hspice simulation results show that,the designed front-end readout ASIC can accomplish the functions of readout and process of the signals from SPM detector,and satisfies the requirements of PET system.