Objective <p>This study aims to analyze the epidemiological characteristics and clinical features of childhood malignant solid tumors in a single center in southwest China, thereby providing a reliable basis for formulating prevention and control strategies and rational allocation of resources for these tumors.</p> Methods <p>Children less than 15&#xa0;years old and under-diagnosed with malignant solid tumors for the first time at Children's Hospital of Chongqing Medical University (Children's Medical Center of Southwest China) from 2000 to 2023 were selected. They were classified according to the International Classification of Childhood Cancer, Third Edition (ICCC-3). A retrospective analysis was conducted on the disease spectrum composition and trends, distribution among different age groups and genders, and hospitalization characteristics of the patients.</p> Results <p>Over 24&#xa0;years, there were a total of 4,777 cases of initial diagnosis of childhood malignant solid tumors, with a male-to-female ratio of 1.33:1. The median age was 4&#xa0;years old, with 12.6% in the 0-year-old group, 41.6% in the 1 to 4-year-old group, 27.3% in the 5 to 9-year-old group, and 18.5% in the 10 to 14-year-old group. The top 3 malignant solid tumors by incidence rate were central nervous system (CNS) tumors (21.8%), neuroblastoma (17.8%), and lymphoma (13.9%). The ratio of pediatric malignant solid tumor patients to total hospital admissions rose from 0.14% in 2000 to 0.52% in 2021 but showed a declining trend after 2021. Childhood malignant solid tumors were primarily diagnosed due to the discovery of mass/occupancy (34.9%), abdominal pain/bloating (21.1%), or fever (6.3%). 74.4% of neuroblastomas and 54.7% of nephroblastomas were diagnosed at an advanced stage. 84.4% of patients underwent surgery, and 71.9% received chemotherapy, with chemotherapy rates showing an upward trend.</p> Conclusions <p>This study provides reliable information on the incidence characteristics and trends of childhood malignant solid tumors.</p>