Abstract: A tow monitoring system was developed in order to deliver a new tow bale to filter rod maker timely. The system mainly consists of a laser distance sensor, a server and a PC terminal. The laser distance sensor is installed on the dustproof cover of the tow bale to measure the distance from the sensor to the top surface of the bale real-timely. The wireless transmission module is connected to the server via the LoRa protocol, the collected data are converted into tow bale's height data and stored in the server. The PC terminal calculates and displays the surplus information of leftover tow in the bale based on their height data, and reminds to deliver a new tow bale in time. The developed monitoring system was tested on 12 KDF4 filter rod makers in Qujing Cigarette Factory. The results showed that there was no need to manually check the tow amount for each maker and no early delivery of tow bale was found. Idle time of filter rod maker due to late delivery of tow bale was reduced by 7.79 min/shift. This technology provides support for the promotion of production efficiency of filter rod makers.