Introducing thermally conductive ceramic fillers to the copper clad laminate (CCL) resin matrix is an effective way to improve its thermal conductivity. AlN is a kind of ceramic filler with high thermal conductivity and good insulation, but its easy hydrolysis has limited its practical application. In addition, compared with the ceramic filler-resin matrix composite system, systematic research on the properties of the filler filled CCL is relatively rare. In this study, AlN was treated with phosphoric acid to obtain pAlN with excellent hydrolysis resistance. Then, the effects of different pAlN particle sizes and filling amount on the thermal conductivity, peeling strength, dielectric properties and other properties of AlN-filled CCLs were investigated. Finally, the pAlN gradation filling strategy of different particle sizes was adopted to explore the influence of different gradation schemes on the performance of the CCLs, of which the CCL with the best gradation and excellent comprehensive performance was obtained. The results show that the thermal conductivity of CCL insulating layer increases to 0.757 W/(m·K), 160% higher than that of pure resin CCL under the optimal gradation of pAlN-50 μm60%-5 μm5%. It displays excellent mechanical properties ( peel strength of 1.012 N/mm and bending strength of 335 MPa), dielectric properties (dielectric constant of 4.499 and dielectric loss of 6.668×10^-3), and the water absorption which is as low as 0.53%. All these data could be a promising guidence for CCL application.