A roof dynamic state monitor for a comprehensive mechanization filling coal mining goaf is composed of a monitor base, a multi-level telescopic rod and an underframe. The monitor base is composed of a base cylinder, a spring, a transmission cable, a pattern displacement meter and a guide rod, wherein a displacement meter support, a protective port, a spring support and a range limiting plate are arranged in the base cylinder, the pattern displacement meter contains a chip, the base cylinder is fixed on the underframe with screws, the spring is arranged in a clamping groove of the spring support, the pattern displacement meter is arranged in a clamping groove of the displacement meter support, the guide rod is directly connected to the pattern displacement meter, the guide rod and the pattern displacement meter are arranged in the spring in a sleeved mode, and the transmission cable is connected with the chip. The multi-level telescopic rod is composed of a first-level rod body, a second-level rod body and a third-level rod body, wherein the first-level rod body is installed in the base cylinder and is in direct contact with the range limiting plate on the guide rod, the second-level rod body is fixed in an installation groove of the first-level rod body through a fastening bolt, and the third-level rod body and the second-level rod body are fixed through a fixing bolt. The roof dynamic state monitor can directly and accurately monitor the dynamic subsidence of a roof and is ingenious in structure and convenient to use.