：近年来，在线知识问答平台从传统的免费模式衍生出付费模式，且越来越多的用户开始参与付费知识问答活动。文章选取用户标识视角来探索其对回答者从免费到付费知识问答平台转移行为的影响。首先，对回答者参与在线知识问答平台中的影响因素进行了梳理。随后，爬取了回答者在免费和付费知识问答平台中的行为信息，并对其行为特征进行分析。接着，利用倾向得分匹配法研究用户标识对回答者从免费到付费知识问答平台转移行为的影响，并对分析结果的稳健性进行了检验。研究结果表明，进行个人认证对回答者的转移行为并未产生显著影响，而获得优秀回答者称号则正向显著影响了回答者从免费到付费知识问答平台的转移行为。

Recently, pay-for-answer model has been evolved from the traditional free-based social question and answer platform (Q&A), and more and more users have been involved in the payment-based social Q&A activities. This paper investigates the impact of user identity on the answerers' switch behavior from free- to fee-based knowledge Q&A platforms. First, the study presents a literature review on the influencing factors of participants’ motivations and behaviors in online knowledge Q&A platforms. Then, we crawl the answerers’ behavioral information in both free- and fee-based knowledge Q&A platforms, and conduct some preliminary analysis. Furthermore, the propensity score matching method has been employed to examine the impact of user identity on the answerers' switch behavior, and the robust test has been conducted and verified. The research findings show that the certification of answerers‘identity does not have a significant impact on the answerers' switch behavior, while the title of excellent answerers has a positive significant impact on the answerers' switch behavior.