The invention discloses a metallization and heat sink integrated preparation method of an AlN ceramic substrate. According to the preparation method, a Ti metallization layer, a Ti-Cu gradient transition layer and a Cu heat sink layer are sequentially formed on the AlN ceramic substrate by the aid of a physical vapor deposition technology, and a transition layer Al3Ti+TiN is formed between an AlN layer and a Ti layer in the deposition process. The method specifically comprises the steps that surface polishing treatment is performed on the AlN ceramic substrate; the polished AlN ceramic substrate is soaked, cleaned and then dried; the surface of the cleaned AlN ceramic substrate is sequentially plated with the Ti metallization layer, the Ti-Cu gradient transition layer and the Cu heat sink layer by the aid of a magnetron sputtering deposition method, in the deposition process, the transition layer Al3Ti+TiN is automatically formed between the AlN layer and the Ti layer, and finally, the metallization and heat sink integrated AlN ceramic substrate is formed. According to the method, the metallization and heat sink integrated plating layer is deposited on the AlN ceramic substrate by the aid of the high vacuum magnetron sputtering technology, so that the overall packaging strength is greatly improved, the packaging process flow is shortened, the packaging consumption is reduced, and the production cost is remarkably reduced.