源中子脉冲的脉宽和滞空是脉冲快热中子分析技术的两个关键时序参数，但目前国内外还没有针对上述参数的量化评估及设置方法的相关文献报道。针对这一现状，定义了时序优化的量化评估函数，进而建立了一种时序参数优化的理论解析模型，并通过将待测目标物与周边介质等效为线性时不变系统，简化了计算过程。从数学上证明了基于该模型获取的中子脉冲的最优脉宽和滞空应相等。以美国研制的脉冲中子元素分析仪应用于地雷探测时的场景为例，获取了该场景下的最优时序参数，并论证了该模型对环境介质、探测布局的适应性。结果表明，该理论模型能快速有效地获取特定应用场景下的最优时序参数，且对探测背景、探测布局均具有较强的适应性。提出的理论模型可为脉冲快热中子分析技术应用于物料分析、违禁品探测、地雷探测等领域提供参考。

The duration and the interval of the pulsed source neutrons are two key timing parameters of PFTNA (pulsed fast/thermal neutron analysis) method. However, there are still no relative literatures about the evaluation and the setting of these two parameters, both at home and abroad. A function S was established to quantitavely evaluate the parameters, and then a theoretical model was proposed to obtain the optimal timing parameters. The calculation process was simplified by regarding the target object and surrounding mediums as a linear time invariant system. It was mathematically proved that the optimal duration and the interval had the equal value. The scenario of PELAN applied to landmine detection was chosen to expound the detailed calculation procedures based on the above-mentioned theoretical model. Furthermore, adaptability of the model to the surrounding medium and that to the detection layout were also fully tested. It was illustrated that, optimal timing parameters of the PFTNA method can be easily obtained through the theoretical model, meanwhile the model showed a strong adaptability to both the surrounding medium and the detection layout. Effective reference timing parameters could be provided when PFTNA method was applied to the fields like material analysis, contraband detection and landmine identification.