Abstract: The recent achievements on GaAs MMIC technology at Nanjing Electronic Devices Institute (NEDI) were reviewed in this paper. Based on our practice, devices (MESFET, PHEMT and HBT) modeling technique and MMIC CAD technique were discussed in detail. Relying open MMIC process developing (ion-implanted MESFET, PHEMT and HBT, by using 3inch GaAs wafers)at NEDI, various device models including that for small signal, large signal and switching application were developed. The models have been used successfully for the development of various MMICs for power, receiving and control circuit use in the last years. Some developed MMIC results including the MMICs for handset use were summarized as the samples in the paper.