A power miter saw is provided with a base including positioning apertures; a table rotatably mounted on the base and including an arm projecting forward; a saw blade and motor mechanism configured to rotate a circular saw blade thereof; a pivotal positioning seat interconnecting two linear guide mechanisms and a support seat at a rear end of the base; a connecting seat interconnecting the linear guide mechanisms to the saw blade and motor mechanism; a locking device; and a positioning device. Knob rotation and button pressing may adjust a rotational position of the table.