The incidence of malignant tumors diagnosed during pregnancy is increasing, often ascribed to the recently recognized trend that many women are postponing childbirth. Although early diagnosis is optimal for both mothers and fetuses, the diagnosis of malignant tumors during pregnancy is often delayed until an advanced stage, because generalized symptoms of pregnancy and malignancy may overlap, such as shortness of breath, chest or abdominal discomfort. The study patient was 21 years old, and 31 weeks-pregnant when she was diagnosed with primary tracheal adenoid cystic carcinoma (ACC). The patient initially presented with dyspnea and decreased blood oxygen saturation and underwent a cesarean section on the first night of hospitalization, resulting from fetal distress. This case report intended to investigate potential barriers to the timely diagnosis of tracheal ACC and consider optimal management strategies when it is diagnosed during pregnancy.