The systems including an electronic control unit (ECU), liquefied petroleum gas (LPG) supply system and LPG electronic control injection system were developed, by which a 295T DI diesel engine was successfully refitted. Subsequently, taking respectively diesel oil and LPG / diesel as fuel, under the same condition, performance tests of the modified engine were carried out. Results indicated that the refitted engine’s power performance increased in a quite big range, economy performance became better, and Nox emission was lower; the CO level is closed to that of the prototype diesel engine; but the HC emission level was higher in low load stage and was lower in full load stage compared with prototype diesel engine. The research results also prove that our refitting scheme is feasible.