Abstract: To address issues such as prolonged downtime, high reliance on manual intervention, and low efficiency associated with traditional offline upgrade methods for underground coal mine bus devices, a low-bandwidth differential upgrade method for coal mine bus devices is proposed. This method, based on differential compression algorithms and substation collaborative control, optimizes differential package generation mechanisms and multi-level verification strategies to achieve efficient concurrent upgrades across multiple devices. The upgrade framework adopts a collaborative working mechanism combining the bsdiff differential algorithm and the Lempel-Ziv-Markov chain-Algorithm (LZMA). The host configuration software identifies device version and type information, matches old and new version source codes from the program library, uses the bsdiff algorithm to extract differential information (identical, offset, and new code segments), and generates an initial differential package. This package is then secondarily compressed via the LZMA compression algorithm to form a lightweight upgrade package, which, after adding header information, becomes the final differential upgrade package. A multi-device collaborative upgrade architecture is designed, in which the substation allocates independent storage space for each bus device. Through a data hybrid transmission architecture and a resource scheduling optimization model, dynamic bandwidth allocation and priority scheduling between upgrade data and regular communication data are achieved. Upon receiving data, the bus device temporarily stores the upgrade package in the APP2 storage area. Based on the header metadata, dual verification is performed using the cyclic redundancy check (CRC) and message-digest algorithm 5 (MD5). After successful verification, the decompression process is initiated, and the bsdiff algorithm is used to reconstruct the new version in the APP3 area by combining it with the existing program in the APP1 area. The Bootloader migrates the upgrade program to the APP1 main execution area via memory copy. After a second MD5 verification ensures data consistency, the version switch is completed. Experimental results show that the upgrade method supports concurrent upgrades across various bus environments such as RS485 and CAN. Compared with traditional methods, the upgrade time for a single device is reduced by over 65%, and the differential package compression rate exceeds 68.2%, significantly enhancing the efficiency and reliability of underground coal mine bus device upgrades.