Abstract: The original control system in KDF2 filter rod maker was out of date,frequent in failures and tough in maintenance.The control system was improved with SIEMENS S7-300 PLC and PROFIBUS-DP,mainly including:the speed regulation system of main motor,rejection of filter rods made at the moment when starting or stopping the machine or wrapped by spliced paper;bobbin change over;temperature control system;and malfunction monitoring.The hardware design included system hardware structure and configuration,and software design included touch screen program and S7-300 PLC software program.The improved system elevates the running efficiency and automation of the machine,reduces material consumption,and facilitates machine operation and maintenance.