Online frauds rose in the second quarter as criminals purporting to be from banks, online finance firms and e-commerce sites targeted high-value transactions, online security firm 360 said.
On the other hand, the volume of spam messages decreased, though residents in major cities, including Shanghai, Beijing and Guangzhou, still suffered from messages and calls, 360 said in its latest mobile security report.
Online fraud victims in China lost 17,582 yuan (US,548) on average in the quarter, double the 8,213 yuan in the same period last year.
A total of 6,870 online fraud cases were reported from April to June with losses of 120 million yuan.
Transfers by mobile bank applications, payment by barcodes and transactions via WeChat and Alipay still have loopholes and potential risks, according to industry experts.
A total of 2.34 billion spam "short messages" were found in the second quarter, half last year's level, 360 said.
Since 2016, the Ministry of Industry and Information Technology, and carriers including China Mobile, China Telecom and China Unicom, have been taking efforts to block spam and crack down on illegal organizations.