According to Spearman correlation analysis of immune score and YTHDC2 gene expression, our study found that YTHDC2 was critically involved in the immune infiltration of cancers, especially in COAD, KIRC, LIHC, LUAD and PAAD, due to the positive correlation between YTHDC2 expression and the infiltration levels of CD8+ T cell, CD4+ T cell, neutrophil, myeloid dendritic cell, macrophage and B cell. The gene discussed is CD4; the disease is cancer.