The invention discloses a multifunctional assembling-type paintbrush. The multifunctional assembling-type paintbrush comprises a brush head, a lighting device, a brush sleeve, a brush handle, a button cell and a flexible rule. A fixing ring is arranged at the right side of the brush head, and threads are engraved in the fixing ring. The fixing ring is fixed to the brush handle through the threads, and the brush head is connected with the brush handle through the fixing ring. The lighting device is installed on the brush handle, and is arranged at the right side of the fixing ring. The brush sleeve wraps the brush handle, and an antiskid sleeve is arranged on the brush sleeve. The lighting device is connected with the button cell through a wire, and the button cell is installed inside the brush handle. A storage groove is formed in the right side of the button cell, and a standby brush head is installed in the storage groove. Sliding rails are installed on the inner wall of the right side of the brush handle. The flexible rule is fixed to the inner wall of the brush handle through a fixed pulley. The multifunctional assembling-type paintbrush has multiple purposes, the trouble of carrying multiple brushes is saved, and losing is not likely to happen. Moreover, the paintbrush is provided with the brush sleeve, the brush handle and the brush sleeve can be protected, and thus the service life of the paintbrush is prolonged.