In view of inconsistent volume design ideas and various volume design schemes of sumps in liquefied natural gas (LNG) terminals，this paper studies the leakage through holes and evaporation diffusion of LNG terminals and adopts numerical calculation method to establish the calculation model of leakage and evaporation amounts.The paper also carries out calculations according to the actual engineering data and compares the calculation results.The results show that if the leakage duration is less than 5 min，the relationship between the leakage amount and the leakage aperture is not obvious；if the leakage aperture is less than 25 mm，the relationship between the leakage amount and the leakage duration is not obvious.In addition，the difference between the leakage point pressure and the flow velocity in the pipe has no significant influence on the leakage amount.Evaporation duration greatly affects LNG evaporation amount，but the ambient temperature has no significant effect on LNG evaporation amount.The leakage amount at the terminal is much larger than the evaporation amount，so the influence of the evaporation amount can be ignored in the volume design of the sump.This paper obtains reasonable and reliable LNG collection amount by calculating the leakage amount of the terminal according to the leakage duration of 10 min and the leakage aperture of 50 mm.