本研究係設計能符合引擎控制器閉迴路測試用途的引擎轉速模擬器，期能有效縮短引擎控制器軟硬體開發維護期程及降低測試人力、油及電等資源成本。 本研究依系統辨識理論循序發展，先以實驗量測燃油閥電壓命令及引擎轉速數據，再運用最小平方辨識法辨識出引擎系統數學模式，然後以 程式語言建立數位引擎轉速模擬系統並進行驗證，最後，使用 公司生產的 實驗板搭配 數位訊號控制器實現引擎轉速模擬器。 本研究所設計的引擎轉速模擬器經與控制器閉迴路驗證結果，符合引擎控制器軟硬體開發維護所需之測試用途。未來如有功能需調整精進，可參照本論文功能方塊圖及程式流程圖修訂。 關鍵字：系統辨識、最小平方辨識法 ;The thesis is to design an Engine Speed Simulator for the closed-loop testing of the engine controller in order to shorten the time spent for software and hardware development and maintenance of engine controller and reduce the costs of oil, electricity and human resource spent for engine controller test. This research is developed sequentially according to the system identification method. First, the data of fuel valve voltage command and engine speed was measured through experiment. Second, the engine system mathematical model was identified by using Least Square Identification Algorithm. Third, based on the model, a digital engine speed simulator and verification system was developed by using Matlab programming language. In the end, we implement an Engine Speed Simulator by using MPLAB C30 target board with dsPIC30F4011 MCU which was produced by Microchip. The Engine Speed Simulator, designed by this thesis, was verified through the closed-loop testing with an engine controller. The experiment result shows that the Engine Speed Simulator meet the requirement of engine controller test for software and hardware development and maintenance. If any improvement of this research is required in the future, the functional block diagrams and program flow charts of this paper will be helpful.