We measured the electronic properties of Two Dimensional Electron Gas in AlxGa1-xN/GaN ¡]x=0.18¡^heterostructures at low temperature and high magnetic field by Shubnikov-de Hass(SdH) for different width. First, we measurement the electronic properties by Ven der Pauw at 300 K and 77 K. For the series sample¡Awe found that 80 nm,100 nm,900 nm sample have PPC (positive persistent photoconductivity effect) properties. The other samples did not change carrier concentration obviously for long illumination time.