The availability1of information in many languages on the Web allows multilingual searchers to search in multiple languages at the same time. Few studies have examined how multilingual web users seek information in two or more languages online, specifically how they switch languages in order to get satisfying search results. This research investigates native Chinese web users' code-switching (Chinese-English) search behaviors in their information seeking process through diary studies interviews. Results indicate that they usually switch languages when they need translation, search for domain knowledge, news and entertainment information, and academic resources, go online shopping, seek personal health information, and need social networking. Findings highlight when the participants need prompt information, they search in Chinese in order to get an immediate understanding. They seek information in English for better resources, which can offer them appropriate information and help them search effectively. We also find that these multilingual users use situational code-switching when the search tasks require them to switch languages in order to get effective and sufficient search results. The role of each language is different in the situational code-switching. When web users switch languages due to emotional or attitude changes associated with complex social or cultural context, they use metaphorical code-switching in order to get satisfying search results. The study aims to provide implications for website design concerning multilingual web users’ code-switching search strategies, habits, and needs.