The invention provides a pressure on-line dynamic monitoring device of a diesel oil engine fuel oil supply system. The pressure on-line dynamic monitoring device comprises multiple pressure sensors, a simulation signal acquisition module, a data processing system and an alarm. The pressure sensors acquire pressure values at different segments of oil feeding pipelines in the diesel oil engine fuel oil supply system. The simulation signal acquisition module carries out conditioning and analog-digital conversion on acquired simulation signals of the pressure sensors, and transport the obtained pressure data to the data processing system. The data processing system analyzed the obtained pressure data and judges whether the pressure data is in a proper fluctuation range. If the pressure data exceeds the fluctuation range, the alarm connected with the data processing system is started to give out an alarm about abnormal pipeline pressure. According to the invention, dynamic monitoring and analysis of pressure at multiple points of the engine fuel oil pipelines; troubleshooting time for faults like hunting of a diesel engine and unqualified power caused by abnormal fluctuation of diesel oil supply is effectively reduced; and working efficiency of scientific research is improved.