A hand-held power tool for pruning and cutting vegetation and a method for replacing blades thereof. The hand-held power tool has a main body and a work head detachably mounted on the main body. The main body has a housing, a motor placed in the housing, and a first gear transmissively connected with the motor. The work head has a blade assembly and a second gear. The second gear engages with the first gear and is provided with a eccentric member connected with the blade assembly. By arranging one portion of the transmission mechanism on the work head, especially the second gear used for providing the eccentrically rotary output on the work head, the transmission mechanism is directly connected with the blade assembly. When the work head needs to be mounted on the main body, it only needs the second gear to be placed on the mandrel arranged on the main body where it will engage with the first gear. This avoids the need to align and mate the eccentric member arranged on the second gear with the upper and lower blades one by one thereby providing an assembly process that is simple and time-saving while providing a connection that is reliable.
