The growing usage of online crowdfunding platforms has fundamentally changed the traditional modes of fundraising and donation. Previous studies have mainly focused on the performance and ethical issues of online crowdfunding. In contrast, there is a dearth of information about the complexity of online donation behaviors. To explore the characteristics of fundraising and donation in online crowdfunding campaigns, we conduct a comprehensive analysis of fundraising and donation behaviors based on 151163 campaigns, with 188955849 donations created from 2016 to 2020 in one of the most popular medical crowdfunding (MCF) platforms called Easy Fundraising in China. We propose four indicators, namely, diversity, uncertainty, concentration, and consistency, to characterize the preferences of individual donors in choosing the donation amounts. Furthermore, we investigate the fundraising temporal dynamics and collective donation characteristics of crowdfunding campaigns using statistical methods. Results show that the first three days after the creation of a crowdfunding campaign is the most efficient fundraising period that largely determines the completion of the campaign. Donors who donate early are more generous than those who donate later. Individual donors prefer donation amounts in multiples of five, such as 5, 10, 20, and 50, and rarely change their donation amounts, which is irrelevant to the patients’ locations. The empirical results obtained in this study provide valuable insights to improve crowdfunding management, public welfare systems’ construction, and human donation behaviors’ understanding.