An arrayed waveguide grating ,which is applied to IEEE 200/400 GbE standard 802.3 bs, is designed and manufactured. The arrayed waveguide grating uses the silica-on-silicon material, which has 2.0% ultra-high refractive index difference, making the less chip size and insertion loss. In addition, in order to obtain a flattened receiving spectrum, the output waveguides are widened and the multimode waveguide structures are used to excite a few of higher order modes. Several patterns are overlaid so that the top of the original Gaussian spectrum is flattened and forms a box-like receiving spectrum. At last, the designed center wavelength of the arrayed waveguide grating is 1 291.10 nm, the channel spacing is 800 GHz, and the device size is 11 mm×4 mm. The microchip is manufactured by plasma enhanced chemical vapor deposition and inductively coupled plasma etching. The test results show that, the minimum insertion loss is about －3.3 dB, the crosstalk between adjacent channels is less than －20 dB, and the single channel 1 dB bandwidth ranging from 2.12 nm to 3.06 nm, realizing a good wavelength demultiplexing and flattening effect, and having a certain practical value in the actual optical communication system.