This study for preparation of aluminum nitride (AlN) with high purity was carried out by self-propagating high-temperature synthesis method in two different systems, Al-N$_{2}$ and Al-N$_{2}$-AlN, with the change of nitrogen gas pressure and dilution factor. On the occasion of Al-N$_{2}$ system, unreacted aluminum was detected in the product in spite of high nitrogen pressure, 10 MPa, This may be caused by obstructing nitrogen gas flow to inner part of molten and agglomerate of aluminum, formed in pre-heating zone. In Al-N$_{2}$-AlN system, AlN with a purity of 95% or ever can be prepared in the condition of f$_{Dil}$ $geq$ 0.5, P$_{N$_{2}$}$</TEX> $geq$ 1 MPa, and the purity can be elevated to 98% over in the condition of f$_{Dil}$ = 0.7 and P$_{N$_{2}$}$</TEX> = 10 MPa.