The invention belongs to an auxiliary tool of a disk saw, and particularly relates to a multifunctional protective cover of the disk saw. The multifunctional protective cover of the disk saw comprises a casing; the lower end of the casing is opened; the casing is arranged in the mode of doing reciprocating motion in the vertical direction; two loose-leaf type end plates are arranged on the casing and correspond to the front end and the back end of the disk saw; the upper ends of the two end plates are hinged to the top wall of the casing, so that the two end plates can warp towards the front end and the back end of the casing correspondingly, and the two end plates and the top wall of the casing form an arch-shaped baffle plate. The protective cover provided by the invention can serve as an enclosing device to enclose the disk saw when the disk saw does not work so as to prevent the disk saw from accidentally injuring the surrounding workers; the protective cover also can serve as a baffle plate to shelter the upper space of the saw disk in the working process of the disk saw so as to prevent waste residues from splashing and provide effective protection for operators.