With the rapid development of the Internet, online testing is becoming more widely-used in education. The purpose of this study is to explore the learning effectiveness of nursing students using online testing as an assistant tool. The participants were 146 junior college nursing students aged 19 to 20 taking the community health nursing course. With a class as the unit, three classes were randomized and allocated to one experimental group and two control groups. Two structured questionnaires were used to obtain the basic data, and the groups' examination results were also collected. The results of this study showed that before the intervention, there were no significant differences between the experimental and two control groups. After the intervention and adjusting for potential confounders, the score of midterm test in the experimental group was significantly better than those of the control groups. Over half of the students felt that answering 21 to 30 questions in 31 to 60 min for one unit of testing were appropriate. The results of this study showed that online testing is feasible for use as an assistant tool for learning. However, the positive effects of this approach appeared to be short- rather than long-term, and thus more studies are required in future.