Abstract: The sodium spray fire experiment was carried out in a closed pressure vessel of 2.4 m³, to evaluate the thermal and pressure responses of sodium spray fire. The liquid sodium of 250 ℃ was sprayed downward by an electromagnetic pump into the vessel in the form of sodium droplets through a nozzle with a diameter of 2.4 mm located 1.35 m from the bottom of the vessel, resulting in sodium spray fire. The sodium flow rate was about 14.85 g/s, and the spray duration was 78 s. The burning of sodium produced a maximum pressure of 41 kPa at 78 s and a maximum temperature of 190 ℃ at 113 s. The experimental data and estimation data calculated by a computer code based on NACOM (sodium spray fire code) were compared and discussed. The results show that with revised sodium flow rate of 3.83 g/s, and the total heat transfer coefficient of the vessel wall of 9.6 W/(m²•K), the post-test estimation of pressure calculated using the computer code exceeds actual pressure measured during the period of sodium spray, and in good agreement with that following termination of the sodium spray. However, there is a big difference between the calculated and experimental temperatures. Based on calculation, the maximum temperature of the vessel gas is 303 ℃ at 78 s, probably due to the lagging effect of the temperature measured by the thermocouples.