A push-the-bit rotary guiding device includes a mandrel having a central passage, a sleeve rotatably sleeved outside the mandrel, a plurality of swing ribs circumferentially arranged in an outer wall of the sleeve with an interval, an actuation mechanism for controlling each swing rib to swing respectively, a plurality of detectors for detecting a distance to a well wall in real-time, and a controller for determining whether the actuation mechanism is required to actuate the swing ribs to swing according to the detected distance. Through a real-time detection of the detectors of the push-the-bit rotary guiding device, a well section having an expanded or reduced diameter is detected in time and guiding of the rotary guiding device herein is avoided. The rotary guiding device has advantages of a simple and compact structure, convenient machining, easy assembling, and a safe and highly-efficient operation, and is easy to be popularized and applied.