Purpose <p>The purpose of this study was to investigate the aesthetics evaluation of four smile-related characteristics among different genders and professional subgroups, including dental professionals (DPs), non-dental healthcare professionals (NDPs), and laypersons (LPs).</p> Methods <p>Smile photographs were selected and digitally manipulated to determine changes in various smile aesthetic parameters (lip thickness ratio, smile line/smile index, upper lip curvature, and smile arc/dental curvature). These altered images were rated by Chinese participants (dental professionals, non-dental healthcare professionals, and laypersons). A total of 1469 subjects were recruited to complete the questionnaire. Smile aesthetics ratings were calculated, and comparisons between groups were made.</p> Results <p>All respondents chose 1:1.5 lip thickness ratio, average smile line, upward upper lip curvature, and upward dental curvature (consonant smile arc) parallel to the lower lip curvature smile arc as the most attractive. Dental professionals (DPs) more focus on smile aesthetics compared to the others(<i>p</i> &lt; 0.01). Significant differences were detected in the perception of smile-related characteristics across gender and professional subgroups(<i>p</i> &lt; 0.05). In addition, there were significant differences in the attractiveness ratings for smiles among professional subgroups(<i>p</i> &lt; 0.05). The most important factor influencing smile aesthetics in the present study was smile arc.</p> Conclusion <p>The smile-related characteristics of the smile, such as the lip thickness ratio, smile line, upper lip curvature, and smile arc are predominant factors influencing smile attractiveness and should be given priority when considering and managing aesthetic treatment plans. Females and DPs are more critical of smile aesthetics, and DPs are also focused more on smile aesthetics than laypersons. So it is necessary to account for the influence of gender and profession on personal evaluation and treatment plans.</p>