A buckle mechanism of a dust collecting barrel of a bag-type dust collector includes a first retaining seat and a second retaining seat. Two sides of the first retaining seat are provided with two first linking members. Two sides of the second retaining seat are provided with two second linking members. The first linking members and the second linking members are connected through two connecting rods. An operating rod is provided between the second linking members. A support unit is provided between the first linking members. The support unit is fixed to a barrel cover. The second linking members are driven to swing by the operating rod and the first linking members are linked so that the barrel cover is moved up and down to quickly complete the assembly and disassembly of a dust collecting barrel.