Modern technologies have created many uncertain risks and led human beings into a self-confrontation risk society. Information is an important and useful reference to eliminate uncertainties arising from technological risks. The government, as an authoritative source of information in risk governance, has a predominance of defining risk in the society. In the communicative process, however, the government either greatly depends on technological experts' opinions or makes its own decisions arbitrarily. The voices of lay people are often excluded. The public is suspicious of risk information as interpreted by the government. In order to shorten the perceptional gap between the government and the public, a great, transparent, and participatory mechanism in risk communication in society is needed. Civic participation becomes a significant factor in the application of the public's understanding of the science of risk communication. The aim of this study is to discuss the public's understanding of technological risk through an online mechanism of the democratization of science. This study took a close look at the case of melamine milk powder in Taiwan, though the powder originated from mainland China in 2008 and quickly spread to Taiwan. The theoretical approach of a public understanding of science was applied to explain the process of risk communication between the government and the public in the case study of Taiwan. Research questions were asked: How did the government interpret technological risks? To what extent did online lay people understand and respond to technological risks shaped by the government? Research methods deployed in this study include secondary analysis of the relevant news releases from the government, discourse analysis of an online discussion board, and in-depth interview with the users of the online discussion board who also had children under the age of three. This study argues that the Taiwanese government relied heavily on objective scientific evidence to deal with technological risks. Unfortunately, the government neglected the spread of technological risks coming from lay people' subjective perception. In other words, the government lost a primary chance of defining technological risks and later ignored the zero risk that lay people could tolerate. This resulted in a crisis of legitimization of public policy. After being disappointed, lay people tended to look for alterative information and personal experiences through online resources. Although the Internet can be used for a social basis of learning technological risks, there is online distrust, such as rumors and wars of words. Online lay people, in fact, knew of technological risks and the necessity of debating pseudodox. However, they lacked proper dialogue mechanisms to respond to public policy. This study suggests that the government can set up an online platform for integrating risk information in which different actors in society can participate in the production of knowledge.