The invention provides a Modbus serial-port data processing method. A main thread parses a serial-port configuration file. A serial-port thread is used to be started according to commands of the mainthread, and enters event message cycles. A protocol thread is started, determines serial-port numbers according to serial-port configuration information, and stores Modbus commands, which are stored in a Modbus list of the serial-port thread, into a QModbusComList list of the protocol thread. A data thread is started, parses response information, detects, in real time, whether the QComDataList list stores data, and carries out processing when it is detected that the data exist. According to the method, multiple parallel serial ports are adopted on the basis of a Qt application program framework, a utilization rate on hardware is higher, resources consumed by a system are lesser, long-time collection, analysis and storage of an application program on Modbus data of the multiple serial portscan be guaranteed, and timely, highly efficient and accurate presentation of substation main-equipment status information to a user can be ensured.