The invention provides an accumulated snow phenological information fusion method and system based on multi-source remote sensing data, and the method comprises the steps: obtaining the accumulated snow phenological initial information sequences of at least three satellites in a preset time period; selecting a reference sequence in each accumulated snow phenological initial information sequence; determining each accumulated snow phenological information standard sequence according to each accumulated snow phenological initial information sequence through a standardization algorithm; and determining an accumulated snow phenological real sequence through each accumulated snow phenological information standard sequence and the reference sequence through a back-stepping algorithm. The method provided by the invention determines the accumulated snow phenological real sequence through selecting the reference sequence and the standard references and employing the back-stepping algorithm. The method can employ the advantages of the multi-source remote sensing data in inversion of snow information, reduces the uncertainty of single-source remote sensing data, and improves the accuracy of multi-source remote sensing data.