Pericardial fluid analysis is an important guide for the diagnosis and treatment of pericardial diseases. At the same time, the results of pericardial fluid analysis should be evaluated in combination with clinical symptoms and other examination indicators such as serological tumor markers, autoantibody markers and tuberculosis markers. Pericardial fluid analysis can establish viral, bacterial, tuberculosis, fungal, cholesterol and malignant pericarditis. The results of pericardial effusion analysis should also be combined with the clinical presentation. In patients with suspected malignancy, cytology and tumor markers such as carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), glycoconjugate antigen CA 125, CA 72-4, CA 15-3, CA 19-9, CD-30, CD-25 should be examined. In patients with suspected tuberculous pericarditis, antacid mycobacterial staining, Mycobacterium bovis culture, adenosine deaminase (ADA), gamma interferon and PCR for tuberculosis should be checked. increased CEA and decreased ADA (adenosine deaminase) can differentiate tumor from tuberculous pericardial effusion. In addition, higher levels of ADA have a predictive value for pericardial constriction. However, it must be recognized that for the diagnosis of TB, PCR sensitivity is similar to ADA (75% vs. 83%), but the former is more specific (100% vs. 78%). For suspected bacterial infection, 3 simultaneous cultures of pericardial fluid and peripheral blood for anaerobic aerobic bacteria should be performed. Pro-cardiac viral PCR analysis can assist in identifying viral or autoimmune pericarditis. Specific gravity analysis of pericardial fluid (>1015), protein content (>3.0 g/dL; pericardial fluid/serum ratio >0.5), LDH (>200 mg/dL; serum/pericardial fluid >0.6), and glucose (exudate vs leaky fluid: 77.9±41.9 vs 96.1±50.7 mg/dL ) can differentiate exudate from leaky fluid, however, it does not have direct diagnostic value. Glucose values are significantly lower in septic effusions. very low WBC counts support mucus edema; monocytes are significantly higher in malignancy or hypothyroidism; neutrophils can be elevated in rheumatoid disease or cellular infections. Compared with bacterial culture, Gram staining specificity although high (99%), but the sensitivity is only 38%. Combined measurement of epithelial membrane antigen, CEA and waveform protein immunocytochemical staining can help to identify reactive mesothelial cells from adenocarcinoma cells.