A 25-channel 200 GHz arrayed waveguide grating (AWG) based on Si nanowire waveguides is designed, simulated and fabricated. Transfer function method is used in the simulation and error analysis of AWG with width fluctuations. The 25-channel 200 GHz AWG exhibits central channel insertion loss of 6.7 dB, crosstalk of −13 dB, and central wavelength of 1 560.55 nm. The error analysis can explain the experimental results of 25-channel 200 GHz AWG well. By using deep ultraviolet lithography (DUV) and inductively coupled plasma etching (ICP) technologies, the devices are fabricated on silicon-on-insulator (SOI) substrate. This work has been supported by the National Key Research and Development Program of China (No.2016YFB0402504), and the National Natural Science Foundation of China (Nos.61435013 and 61405188). E-mail:zhangjiashun@semi.ac.cn