Al-doped　ZnO　(AZO)　nanocrystalline　aggregates　(NCAs)　were　prepared　by　a　low　cost　colloid　chemistry　method　and　effects　of　the　Al-doped　concentration　on　the　morphological　and　structural　properties　of　the　AZO　NCAs　were　studied.　The　dye　adsorption　ability　of　the　AZO　NCAs　with　various　Al-doped　concentrations　was　also　investigated.　Results　indicate　that　the　doping　of　the　Al　ions　not　only　does　not　change　the　wurtzite　structure　of　the　ZnO　crystal　but　also　can　reduce　the　crystallite　grain　size　and　the　particle　size　distribution　of　the　NCAs,　which　gives　them　a　higher　specific　surface　area　and　dye　adsorption　ability　than　that　of　the　ZnO　NCAs.　The　as-prepared　AZO　NCAs　would　be　a　promising　material　to　be　applied　in　the　dye　sensitized　solar　cells　and　water　treatment.