Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that affects various systems and organs throughout the body, predominantly affecting women of reproductive age. Due to the strengthening of clinical management and the improvement of treatment, pregnancy is becoming more common in SLE patients, which poses serious challenges for obstetricians. At present, the etiology of SLE is unclear and may be related to genetic factors, environmental factors, sex hormones and immune system disorders. Especially, SLE patients have functional abnormalities in the autoimmune system. In pregnancy, the body's immune system undergoes complex changes, the fetus is a homologous hemihedral graft, and a good pregnancy outcome requires the maternal immune system to tolerate it. T helper type 17 (Th17) and regulatory T (Treg) cells are involved in immune tolerance and the body’s defense mechanisms. Treg cells maintain autoimmune tolerance by inhibiting autoreactive lymphocytes, and Th17 cells produce severe mediators to induce autoimmunity. The relative balance between them is crucial to the success of pregnancy.