A diesel engine combustion analysis and control system based on a developed combustion analysis tool and with the Ethernet communication was established. Real time cylinder pressure information was acquired every 0.2 crankshaft angle and sent via the Ethernet of user datagram protocol（UDP） to a combustion analysis and control software， by which combustion indexes were calculated and sent to the engine control unit（ECU） in which closed loop combustion control was applied with these combustion indexes. A verification test made on a 1.9 L diesel engine demonstrates that this combustion analysis and control system successfully acquires real time cylinder pressure information， provides combustion indexes， and has the ability to control engine combustion.