For the first time, a new-type flat focal field arrayed waveguide grating (AWG) demultiplexer, with the focal signals of all wavelengths of operation focusing along a straight line, is designed based on the aberration theory and fabricated based on a newly developed negative tone epoxy Novolak resin (ENR) polymer using electron-beam direct writing. A polymeric four-channel 400GHz spacing flat focal field AWG demultiplexer is fabricated and tested. Four modal images from the output waveguides are observed and the measured transmission spectra is presented. And we make error analysis.