To quantitatively analyze the consequence of LNG leakage in semi-confined space , the diffusion and explosion af-ter the leakage of LNG in a "cold box"under different conditions were simulated by using the CFD software FLUENT .The results showed that the dangerous area with methane content of 5%-15% by volume fraction always exists whether there is ventilation or not , but this area with ventilation is smaller than that without ventilation .The leakage of LNG will cause the temperature in the box decrease , the larger the leakage amount , the lower the temperature decrease , but the ventilation can reduce the temperature decrease to a certain extent .The biggest dangerous area produces the maximum explosion overpres-sure , and the ventilation can reduce the explosion pressure when the leakage amount is small .The existence of obstacles will increase the explosion pressure , the maximum explosion overpressure in this study was 158 kPa, which can cause serious haz-ard to equipments and personnel , so the corresponding requirement of strength should be put forward when designing "cold box".It has guiding significance for safety design and risk assessment of confined space similar to "cold box".%为定量分析半封闭空间内液化天然气（ LNG）泄漏后果，利用计算流体力学（ CFD）软件FLUENT，对不同条件下的“冷箱”内LNG泄漏后扩散与爆炸过程进行了模拟。结果表明：无论通风与否，危险区域（甲烷体积分数为5％～15％）一直存在，但通风时该区域比无通风时小；LNG泄漏后会导致箱内温度降低，且泄漏量越大温度下降越低，但通风在一定程度上能减小温降；当危险区域最大时，发生爆炸产生的超压最大，对于泄漏量小的情况，通风能减小爆炸压力；障碍物的存在会增大爆炸压力，研究中的最大爆炸超压为158 kPa，可对设备与人员造成严重危害，故在设计“冷箱”时须提出相应的强度要求。研究方法与结果对于与“冷箱”类似的受限空间安全设计与风险评估有指导意义。
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