Sales data in China indicate that slim cigarette consumption has increased dramatically over the last few years. This study examined who smoked slim cigarettes and the reasons for adopting these new products. A survey of an online panel from 19 Chinese cities was conducted from October 2018 to April 2019 with 20,055 members aged 16 and older. Among the 31.7% [95% confidence interval (CI) = 30.1-33.4] of panel members who reported currently smoking, 37.7% (95% CI = 34.8-40.5) smoked slim cigarettes. Among smokers, women were significantly more likely to smoke slim cigarettes than men [56.5% (95% CI = 50.8-62.2) vs. 35.5% (95% CI = 32.8-38.1)]. Smokers with a bachelor's degree were more likely to smoke slim cigarettes than those without [41.3% (95% CI = 38.1-44.4) vs. 33.1% (95% CI = 30.0-36.1)]. Most slim cigarette smokers were dual smokers [77.7% (95% CI = 75.3-80.1)], smoking both regular and slim cigarettes. Among dual smokers, 97.5% (95% CI = 96.7-98.3) started smoking regular cigarettes before slim cigarettes. Of the many reasons given for smoking slim cigarettes, 37.0% (95% CI = 34.3-39.7) directly related to harm reduction with another 10.1% (95% CI = 8.4-11.7) reporting their reason as wanting "to reduce consumption of regular cigarettes," a plausible indication of harm reduction. These findings suggest strong interest in harm reduction among the current Chinese smoking population and that the popularity of slim cigarettes is likely to increase, with the more educated as the early adopters. Given the absence of any evidence that these products actually reduce harm, it is urgent that the public health community be on high alert in order to avoid repeating the sad history of low-tar cigarettes, when a supposed harm-reduction product misled the field of tobacco control.