The results demonstrate that high NLR (HR 2.17; 95% CI 1.22–3.88), low hemoglobin (HR 1.56; 95% CI 1.17–2.06), low total protein (HR 1.14; 95% CI 1.07–1.23), low albumin (HR 1.71; 95% CI 1.25–2.34), high LDH (HR 1.54; 95% CI 1.08–2.19), high CRP (HR 1.84; 95% CI 1.49–2.29) and high VEGF (HR 1.70; 95% CI 1.18–2.43) in serum are prognostic risk factors in OS for malignant patients with pleural effusion. The gene discussed is CRP; the disease is Pleural effusion.