Objective To explore the characteristics of tongue image in non-disease populations in terms of different genders and different ages. Methods Digital tongue diagnosis instrument was used to collect tongue images of 286 healthy subjects. Computer vision in combination with manual interpretation was used to obtain the tongue color values

the sublingual veins color values and the morphological indexes of sublingual veins including length of main veins

vessel diameter

and tortuosity. The correlations of the morphological classification of sublingual veins with age and gender were analyzed

as well as the correlation between the color of the tongue surface and that of the sublingual veins. Results Compared to the men′s color values of tongue surface

those of women including TB-R

TB-G

TB-Y

TB-H

TB-I

TB-L and TB-b significantly increased

while TB-Cb

TB-S and TB-a significantly decreased; the color values of women′s sublingual veins including SV-R

SV-G

SV-B

SV-Y

SV-H

SV-I and SV-L increased

while SV-S decreased significantly（P<0.05）. Compared to people <30 years old

those ≥50 years old had significantly lower tongue color values of TB-R

TB-B

TB-Y

TB-I and TB-L

and higher SV-H value of sublingual veins color; people aged 40～49 had decreased tongue color values of TB-R

TB-I and TB-L

and decreased sublingual veins color values of SV-R

SV-G

SV-B

SV-Y

SV-Cr

SV-S

SV-I

SV-L and SV-a（P<0.05）. Compared to people aged 30～39

those ≥50 years old had decreased TB-R value of tongue surface color

and decreased SV-R

SV-B

SV-Y

SV-Cr

SV-I

SV-L and SV-a levels of sublingual veins colors（P<0.05）. The color of the tongue surface was positively correlated with the color of the sublingual veins（P<0.05）

and the color value TB-H of the tongue surface and the color value SV-H of the sublingual veins showed a moderate correlation

with the correlation coefficient of 0.432. There were no significant correlations of the morphological indexes of sublingual veins with gender and age（P>0.05）. Conclusion There are significant differences in the characteristics of sublingual veins in non-disease populations in terms of different genders and different ages. Women′s tongue color of surface and sublingual veins are brighter than men′s with lower overall saturation

and the tongue manifestation is bright in people less than 30 years old while that is relatively dusky in people aged 50 years old or more.