A paper feeding device includes a lower housing, an upper housing, a pickup assembly, a separation assembly, a relay assembly, a paper friction mechanism, an elastic element, a paper speed detector, a first paper feeding assembly, a second paper feeding assembly, a transmission assembly, a motor and a control unit. The control unit controls the paper speed detector to detect paper feeding speeds and the paper speed detector sends signals to the control unit for determining paper feeding conditions. The control unit controls the motor to rotate, and the motor drives the pickup assembly, the relay assembly and the first paper feeding assembly to rotate by virtue of the transmission assembly, and the first paper feeding assembly drives the second paper feeding assembly to rotate, the control unit is capable of adjusting rotating speeds of the motor, so that the paper feeding speeds are stabilized.