Web 2.0时代的到来让古老的翻译活动出现了新的变化，基于网络平台技术支持的志愿者翻译应运而生。本文选取TED发起的TEDTranslators志愿者翻译项目为个案，采用质性研究中常用的扎根理论，利用Nvivo 11质性研究分析软件，通过收集、分析TEDTranslators官方网页上公开的对31位志愿译者的访谈等记录资料，旨在对其翻译动机做出归纳和探讨。研究最后发现，TEDTranslators项目志愿译者的翻译动机包括与他人分享、改变世界和社会、加强理解，获得知识、提高自己的技能、培养个人对视频内容的兴趣、翻译带来正面情绪、群体互动、视频时间短、自我调节和受其它影响等十种，这十种动机又可归纳为内生利己、外生利己、内生利他和外生利他四大类，其中内生利己和内生利他是TEDTranslators志愿译者参与志愿翻译服务的最主要动机，而外在诱因对志愿译者的翻译动机影响不大。

In the age of Web 2.0, translation as an age-old practice has experienced a great deal of change. Volunteer translation, thanks to the technological support of the internet, has boomed over the last decade. This article provides some insights into the motivating factors that prompt people from all over the globe to contribute to the subtitling translation of TED contents. Grounded theory approach is used to analyze the relevant interview materials collected from the official website of TEDTranslators. With the help of the latest version of Nvivo 11, altogether ten motivating factors have been identified, including“sharing with others”, “changing the world and the society”, “enhancing understanding and acquiring knowledge”,“improving the translator’s own skills”,“interest in TED contents”,“positive feelings”, “interaction within a community”, “short duration of videos”, “emotional adjustment”and“other exterior factors”, which can be further categorized into four major types of motivation, namely, interior-based egoism, exterior-based egoism, interior-based altruism, and exterior-based altruism. For volunteer translators involved in TEDTranslators, the strongest motivations are interior-based egoism and interior-based altruism, while the exterior incentives have limited impact on their motivation.