The invention provides a preparation method of 7XXX series in-situ aluminum-based composite material powder for laser additive manufacturing. The preparation method comprises the following steps: heating commercially pure aluminum; after covering with a high-temperature covering agent, raising the temperature and smelting; uniformly mixing KBF4 and K2TiF6; after drying, adding a mixture into a melt; after reacting, sequentially adding a needed intermediate alloy, commercially pure Mg and commercially pure Zn; adding a refining agent into the melt and carrying out degassing and refining; then carrying out gas atomization to obtain the 7XXX series in-situ aluminum-based composite material powder. According to the method provided by the invention, an in-situ TiB2 micron-nano-sized particle enhanced 7XXX series composite material is prepared by adopting an in-situ melt automatic generation and high-temperature gas atomization method; TiB2 particle enhanced aluminum-based composite materialpowder is prepared; TiB2 particles are uniformly dispersed in an aluminum matrix. The aluminum-based composite material powder prepared by the method has a good laser absorption rate and is suitablefor a laser additive manufacturing technology.