Provided is a paper shredder comprising a housing (6) and a paper shredder head (4), wherein a transmission mechanism (5) and a motor are provided in the paper shredder head (4); the motor comprises a motor body (1), the motor body (1) having an output shaft (12) and a motor housing (11) sleeve connected on the output shaft (12); the motor housing (11) is provided with a heat dissipation device, the heat dissipation device comprising an air intake device (2) and an air output device (3); the air intake device (2) has a cold air inlet and the air output device (3) has a hot air outlet; the air intake device (2) is provided on one side of the output shaft (12) and the air output device (3) is provided on the other side of the output shaft (12); at the position where the air intake device (2) is provided on the motor housing (11) there is an air intake hole (13) opened correspondingly to communicate with an inner chamber of the motor housing (11), and at the position where the air output device (3) is provided on the motor housing (11) there is an air output hole (14) opened correspondingly to communicate with the inner chamber of the motor housing (11), such that a relatively isolated and independent heat dissipating air channel is formed internally from the cold air inlet, via the inner chamber of the motor housing (11), to the hot air outlet.