Flake-like AlN powder has broad application prospects as a filler for thermal interface materials (TIMs). However, the difficulty of preparation technology and high cost limit its practical application. In this work, flake-like AlN powder composed of equiaxed micro-particles was successfully prepared by in-situ direct nitridation in nitrogen atmosphere using flake-like Al powder obtained by ball milling as the Al source. The effects of the ball milling process, nitriding temperature and heating rate on the phase composition and microstructure of the products were studied. The results show that the ball milling process can enhance the reaction activity and nitridation rate of Al powder. Increasing the nitriding temperature can improve the nitriding rate of Al powder, but excessive nitriding temperature leads to the inability to maintain the flake-like morphology of the raw material. In addition, increasing the heating rate results in an increase in the particle size of equiaxed micron-particles. When the nitriding temperature is 640 ℃ and the heating rate is 5 ℃/min, the surface of the prepared flake-like AlN powder is compact and smooth, which is expected to be used as a two-dimensional inorganic filler for TIMs.