The invention discloses a fault detection system based on a Modelica model and a method. The fault detection system based on the Modelica model comprises a Modelica model editor, a model solver, a model post-processor, a signal converter, a data processor, a residual error generator, a threshold values detector, etc. The invention realizes system fault detection through adopting Modelica modeling analysis technology. By the virtue of the fact that the Modelica language is easy in modeling, direct in displaying and strong in adaptability, the method can better adapt to the complex system having strong electromechanical hydraulic control coupling; the invention does not need substantial data reverse and hardware investment through the detection method based on the model, shortens the establishment cycle of the fault detection platform, and effectively control the establishment cost. The method disclosed by the invention ca dynamically reflect the fault occurrence condition, enables the detection to be highly efficient and accurate, provides timely information input to the follow up fault isolation and control, effectively stop the further occurrence of the fault and better guarantee the safety of the system and the personnel.