Abstract: Diesel pool fire experiments on different diesel water ratios were conducted under various ventilation conditions. The flame temperature， the radiation heat flux and the mass loss rate were measured， and the fire splash phenomenon was observed in order to analyze the combustion characteristics and the diesel pool fire spread rules. Results show that the diesel pool fire with 1∶1 diesel water ratio is always in the boilover status and the splash continuously occurs in the fire developed stage under natural ventilation conditions; both the temperature and the radiant heat flux reach the maximum value in the continuous splash. With the decreasing of the diesel water ratio， the flame temperature and the radiant heat flux are reduced and the frequency and the intensity of splashing are reduced either. If the air velocity is increased to 1.0m/s， the combustion is intensified significantly by the ventilation speed and the duration time of the developed stage of fire is increased. When the air velocity is further increased to 1.5m/s， the pool fire is hard to reach the developed stage or only last for a short time， which illustrates the negative impact of ventilation velocity increasing.

Key words: diesel pool fire, mechanical ventilation, splash, boilover, diesel water ratio