Accident insurance for older adults has the advantages of low premium, high security, and wide coverage. It has been actively promoted in various provinces of China and can effectively reduce the economic burden of older adults and their families. However, in practice, the willingness of insurance companies to undertake or engage in this project is low because of the high operating costs. One of the strategies that could make the project work properly is increasing the average amount of the insurance purchase. Behavioral insurance theory emphasizes the behavioral factors that influence how people purchase insurance. This study aimed to explore whether a defaulting strategy could promote the purchase of accidental insurance for older adults through three studies. Study 1 analyzed the impact of different default option settings on purchase behavior based on the actual purchasing data from Hangzhou City. Since two of the companies that undertook the promotional work had different settings for the default amount (one and four by default) when selling insurance online, we compared the specific impact of both default options. Study 2 used a quasi-experimental design to compare the impact of different default settings on the number of purchases. Furthermore, we also tried to explore whether different rendering methods (tiling vs. increasing or decreasing) would affect the number of purchases to differentiate the effect from the default options presented in Study 1. Therefore, the second study used a 2 (presentation form: tile vs. increase or decrease) x 2 (default option: five copies vs. one share) factor design. To simulate a real situation, six college students were recruited as insurance salesmen to promote the simulated product in the campus with a leaflet. A total of 171 participants were persuaded to purchase, by asking them to scan the quick response (QR) code with their mobile phone. The system randomly presented one of four designs. Finally, 78 participants completed all the requested information and therefore their data were regarded as valid and came into the final analysis. Study 3 explored the purchasing differences between the default option of five copies and without the default option in a tiled manner. Data collection was recruited during a psychology course, and a leaflet was issued asking the participants to choose to scan for insurance voluntarily. To increase enthusiasm, the participants were told that 20% of them would receive a 30-Yuan reward. Upon completion of the project, the researcher explained the purpose of the study. Finally, a total of 67 participants completed all information among 168 participants who were willing to purchase the insurance. The results of Study 1 demonstrated that setting the default option to a higher number of copies (four copies) promoted the average purchase amount compared to lower number of copies (one share). Study 2 found that setting the default option to the maximum number of purchases (five copies) significantly increased the purchase amount compared to setting the minimum purchase size (one share). The results of study 3 indicated that setting the default option to the highest number of copies can effectively promote the amount of insurance purchased. The three studies consistently showed that setting the default option to a higher number of purchases can effectively increase the purchase amount. The implementation of behavioral science in insurance management should be considered during future implementations of government insurance projects in China.