Objective To study traditional Chinese medicine（ TCM） syndrome factors and syndrome distribution in lung cancer patients with malignant pleural effusion. Methods Retrospective investigation was adopted to collect information about demographic data

the main clinical symptoms

tongue manifestation

pulse condition and syndrome factors of 105 lung cancer patients with malignant pleural effusion. Used descriptive statistical analysis and clustering analysis method to analyze basic syndrome factors and distribution regularity of TCM syndrome. Results The top 10 TCM symptoms of lung cancer patients with malignant pleural effusion were cough

fatigue

anorexia

white sputum

pant and suffocation

choking sensation in chest

poor sleep

shortness of breath

chest pain and little sputum. Top 5tongue manifestation and pulse condition were white moss

red tongue

dark tongue

thin pulse

and thin moss. Distribution of TCM syndrome factors from more to less were Qi deficiency

phlegm-damp

blood stasis

Yin deficiency

Yang deficiency

phlegm-heat

Qi stagnation

and blood deficiency. Clustering analysis identified the syndrome types into 6 classes

and the similarity coefficients among the syndromes were all small. Conclusion The basic syndrome factors of lung cancer patients with malignant pleural effusion were Qi deficiency syndrome

phlegm-damp syndrome

blood stasis syndrome

Yin deficiency syndrome. Basic TCM syndromes were 6 types including cold-damp affecting spleen

Qi stagnation and blood stasis

Qi and Yin deficiency

phlegm and blood stasis

spleen-kidney Yang deficiency

liver-spleen disharmony.