[目的/意义]生成式信息搜索过程中认知负荷的增加可能会导致用户的挫败感和系统切换行为，文章旨在探究生成式信息搜索不同阶段中用户的认知负荷变化模式及成因。[方法/过程]通过实验法收集用户在完成搜索任务过程中的认知负荷数据，使用主观测量法、任务绩效测量法、生理测量法对认知负荷进行测量，并使用单因素方差分析和Welch检验判断不同搜索阶段的认知负荷是否存在显著差异。随后，采用访谈法收集用户实验后的主观描述，并使用主题分析方法归纳搜索过程中认知负荷的成因。[结果/结论]用户的认知负荷在聚焦后阶段最重，聚焦前次之，焦点制定阶段最轻。认知负荷主要来源于用户自身、任务、生成式人工智能系统及用户与系统交互四个方面。

[Purpose/significance] The increase in cognitive load during generative information search may lead to user frustration and system-switching behaviour. This paper aims to investigate the patterns and causes of changes in users′ cognitive load at different stages of generative information search. [Method/process] Cognitive load data was collected using experimental methods whilst users were performing search tasks. Cognitive load was measured using subjective, task performance and physiological measurement methods, and a one-way analysis of variance combined with Welch′s test was employed to determine whether there were significant differences in cognitive load across different stages of the search process. Subsequently, subjective descriptions from users were gathered through interviews following the experiment, and thematic analysis was used to identify the causes of cognitive load during the search process.[Result/conclusion] Users′ cognitive load is heaviest during the post-focus stage, followed by the pre-focus stage,with the lightest load occurring during the focus stage. Cognitive load primarily stems from four sources: the user themselves, the task, the generative AI system, and the interaction between the user and the system.