Objective To explore the features of the traditional Chinese medicine（ TCM） syndromes of senile dementia. Methods Totally 660 senile dementia patients were collected with multi-center cross-sectional epidemiological survey. TCM syndrome information form of senile dementia including general information

etiology and pathogenesis

pulse diagnostic information

syndromes and other related information was completed. Frequency of all symptoms

tongue diagnosis

pulse diagnosis and syndromes was calculated. Factor analysis was done on the main symptoms of senile dementia. Main symptoms and distribution features of TCM syndromes were summerized. Results The top 10 symptoms of senile dementia were forgetfulness

miscalculation

avulsed tooth

grey hair

weakness and soreness in the waist and knees

retarded responses

slowness in walking

fatigue

forgetting things in a glance

dullness in expression. The main syndrome elements were essence deficiency

yang deficiency and yin deficiency. The secondary syndrome elements were blood stasis and phlegm. The location of the disease was mainly kidney

while related to heart

liver and spleen. As for the distribution of syndromes

kidney deficiency took up 86. 36%

followed by qi stagnation and blood stasis（ 5. 15%） and phlegm obstructing orifices（ 3. 94%）. Conclusion The onset of senile dementia was closely related to the kidney. Kidney deficiency was the basis of senile dementia

and blood stasis and phlegm were the key factors of its development and aggravation.