With the popularity of mobile terminals and social media increasing, misinformation about science has increased in China. To understand the nature of the popularity of scientific rumors, we analyzed 206 typical cases released by four authoritative platforms in China from 2010 to 2020. Content analysis revealed that the majority of scientific rumors are related to health and safety (76.8%), use a visual format (61.2%), are published on social media (62.2%), and provide more than three narrative elements (78.2%). In addition, rumors from unidentified netizens’ claims or homemade experiments are the most common (35.9%), followed by highly credible sources, such as expert assertions (20.9%) or scientific research results (19.4%). A further qualitative comparative analysis indicated that a combination of details and fear-mongering are significant conditions that make rumors receive significant attention. Visual presentation also plays an important role, while state media and the presence of scientific terminology have a weak effect.