Abstract: Lattice matched N-polar Ga N/In_0.17Al_0.83N heterojunctions have attracted much attention due totheir excellent material and electrical properties.The material and device properties of N-polar Ga N/In_0.17Al_0.83Nhigh electron mobility transistor(HEMT)were simulated by self-consistently solving the Schrodinger equation andPoisson equation and quasi two-dimensional model.The analysis shows that the increase of Ga N channel layer,In_0.17Al_0.83N barrier layer and Al N insertion layer thickness can improve two-dimensional electron gas(2DEG)sheetdensity and confinement,and the influence degree increases in turn.When the thickness of Ga N channel layer ishigher than 10 nm or the thickness of In_0.17Al_0.83N back barrier layer is higher than 25 nm,the 2DEG surface densitytends to be saturated.The introduction of the Al N insertion layer makes the 2DEG sheet density increase more greatly,and also improves the material quality of In_0.17Al_0.83N back barrier,mobility and confinement in heterojunction.Finally,the quasi two-dimensional model calculation shows that the maximum leakage current and peak transcon-ductance of N-polar Ga N/Al N/In_0.17Al_0.83N HEMT are 160 m A·mm^-1and 84.5 m S·mm^-1,respectively.