Abstract: In order to investigate smoking behaviors and nicotine exposure levels of cigarette smokers after switching to using heated tobacco products, 50 volunteers who regularly smoked cigarettes were recruited and randomly divided into two groups, one switched to a heated tobacco product known as IQOS and the other group to a domestic heated tobacco product M. Their general smoking characteristics were collected via questionnaires and their smoking parameters were recorded by a CReSS pocket analyzer. The contents of nicotine exposure biomarker in the volunteers' urine samples before and after switching were determined by HPLC-MS/MS. The results showed that: 1) The smoking behaviors of the smokers were basically unchanged after switching to the heated tobacco products, the puffing volume and duration did not change significantly. However, the puffing interval of the two groups significantly shortened from (14.3±8.0) s and (15.3±9.0) s to (9.8±8.3) s and (9.7±5.4) s, respectively. 2) The contents of total nicotine metabolites and nicotine exposure biomarkers (i.e. cotinine) in the volunteers' urine samples did not change significantly after switching to the heated tobacco products. 3) There was no significant difference of the smoking behaviors between the volunteers switched to IQOS and those to M, and the levels of total nicotine metabolites and cotinine in the urine samples of the two groups were also quite similar.