Abstract: In order to overcome the clock oscillator's sensitivity to temperature and process,designing and implementing a 1 GHz clock oscillator circuit with process and temperature compensation based on a SMIC 0.18 μm standard CMOS process.The oscillator uses a temperature compensated block and a threshod voltage sensing block. With these blocks,the frequency still has high stability when process and temperatrue change.In the meantime, adding the shaping circuit to form the rail to rail square wave clock signal.Measurements are made in the supply power of 1.8 V,across the process corners ff,tt,ss,and a temperature range of-40℃ to 125℃,they indicate a worst case variation of 2.08% and 2.3% respectively.Achieving the acquirement of frequency stability.