Small cell lung cancer (SCLC) is an aggressive disease characterized by rapid growth and metastases. It has been recognized that the inflammation of the microenvironment plays a critical role in the development of malignancies. However, little is known about the role of multiple inflammatory and hematological markers in the prognosis of SCLC. The aim of this study was to determine the clinical significance of pre-treatment inflammation-based scores and characteristics as prognostic indicators for the survival of SCLC patients. A retrospective analysis of 919 SCLC cases was performed. Patients’ characteristics and hematologic tests data at initial diagnosis were collected. The univariate analysis of all SCLC patients indicated that favorable prognostic factors were age ˂ 70 years, non-smokers, good performance status, limited disease and response to treatment. Moreover, univariate analysis of inflammation-based scores and other blood parameters showed that neutrophil-lymphocyte ratio ≥ 5, platelet-lymphocyte ratio ≥ 250, systemic immune-inflammation index (SII) ≥ 1,600 × 10⁹/L, prognostic nutritional index (albumin + 5 × lymphocyte) < 45, and elevated serum lactate dehydrogenase (LDH) predicted poor prognosis in SCLC patients. SII represents the score that is calculated as follows: platelet count × neutrophil count/lymphocyte count. In the multivariate analysis, SII, together with serum LDH, stage and response to therapy, were associated with overall survival (OS). This study demonstrated that the combination of platelet count and neutrophil-lymphocyte ratio could help to predict poor prognosis in SCLC. Our findings will facilitate the understanding of survival differences in SCLC patients in clinical practice.