The growth and device fabrication of AlGaN/GaN high electron mobility transistors (HEMTs) are carried out by using metal organic vapor phase epitaxy (MOVPE) system.Specially the performances of HEMT devices with different thickness of AlGaN layer are compared.The device with thinner spacer layer exhibits better static performance.And a maximum saturation current density of 650mA/mm and a peak extrinsic transconductance of 100mS/mm are obtained from the devices with gate length of 1μm.