The invention discloses an underground mining scraper conveyor coal bed height control device and a working method thereof. A coal mining machine parameter acquisition module acquires the motion stateof a coal mining machine in real time, generates real-time motion information of the coal mining machine and transmits the real-time motion information of the coal mining machine to a calculation module. A scraper conveyor parameter acquisition module acquires the motion state of a scraper conveyor in real time, generates real-time motion information of the scraper conveyor and transmits the real-time motion information of the scraper conveyor to the calculation module. The calculation modules calculates real-time coal quantity in one time period to obtain the real-time coal bed height of thescraper conveyor in the time period, generates real-time coal bed height signals and transmits the real-time coal bed height signals to a comparison module. The comparison module compares the real-time coal bed height of the scraper conveyor in each sampling period with a set coal bed height. A scraper conveyor speed control module responds to signals transmitted by the comparison module and thenchanges the running speed of the scraper conveyor to control the scraper conveyor coal bed height and keep uniform distribution of coal on the scraper conveyor.