Provided are an anti-fatigue in-situ aluminium-based nanocomposite material for heavy-load automobile hubs and a preparation method therefor. By means of the fine adjustment of components and a forming process, in situ nano-compositing, micro-alloying and rapid compression moulding techniques are combined. That is, after the addition of elements Zr and B, an in-situ reaction occurs to form a nano ZrB2 ceramic reinforcement which is distributed in aluminium crystals and crystal boundaries and bonded to a metallurgical interface kept firm with the matrix. Moreover, with rare earth elements Er and Y and element Zr as addition ingredients and after the increase in the contents of Cr and Mn, a structure having fine aluminium crystal grains with a large number of micro-alloyed nano precipitated particles contained in the grains, fine and round eutectic silicon grains and a fine Mg2Si phase mainly dispersed inside the grains is obtained in the process of the rapid compression moulding and thermal treatment of the hubs; and thus, the tensile strength, the yield strength and the fatigue strength of an alloy are effectively improved.