Researchers found users’ switch from cash payment to mobile payment and we will have a cashless society. many studies were interested in overspending of using non-cash payment methods such as credit cards and debit cards. But few research paid attention to overspending of mobile payment. Mental accounting has been proved to be associated with irrational economic decisions. However, there weren’t enough studies on mental accounting of mobile payment. Therefore, the present study hypothesized mobile payment and cash payment as two different mental accountings, and mental accounting of mobile payment makes one spend more. We also hypothesized that mental accounting effect of pocket change doesn’t exist so that people no longer tend to control their spending of 100 yuan while the effect of windfall gains with mobile phone red packet still exists, resulting in more spending and greater preference for hedonic goods in the mobile payment accounting. 114 undergraduates were recruited in three experiments. In Experiment 1, 47 participants (14 males and 33 females, mage=21.19) were divided into two groups. The experimental group used mobile payment, meanwhile the control group used cash payment to choose goods displayed on the computer screen by E-prime. In Experiment 2, 35 participants (17 males and 18 females, age=21.29) were divided into two groups. One group was given 100 yuan once. Meanwhile another group was given four times but the total amount was 100 yuan. Participants all used mobile payment. In Experiment 3, 32 participants (17 males and 15 females, mage=19.51) were divided into two groups. One group was given windfall gains via WeChat red packets, the other group was given money via regular accounts. Both groups used mobile payment to choose groceries like Experiment 1 and 2. Experiment 1 showed mobile payment group spent significantly more than cash payment group (p<0.01). In the same way mobile payment group had more frequent buying behaviors (p<0.01). Mobile payment users chose more utilitarian goods than cash users (p<0.01). Experiment 2 showed mobile payment users given money four times, non-significantly spent more money than the other users who were paid off once (p=0.277). In Experiment 3, “Windfall gains” group spent more (p<0.01) and bought more frequently (p<0.01) than “regular gains” group. For hedonic goods, “windfall gains” group also spent more money (p<0.01) and bought more frequently (p<0.05). Conclusions are: (1) Mobile payment and cash payment belong to different mental accountings. The former of mobile payment is more inconspicuous of finances going down than cash payment. Using mobile payment makes one feel less pain and spend more money. Besides, Consumers are much willing to spend cash on utilitarian goods. (2) In the mental accounting of mobile payment, the principle of “control major, ignore minor” is not prominent. Participants didn’t tend to control their consuming of large money. (3) Mobile payment accounting exists the windfall gains effect with mobile phone red packets. With windfall gains, the consumption sum is higher and participants inclined to hedonic consumption. Key words mobile payment, mental accounting, pain of paying, cashless society