This paper introduces the clinical experience of Professor Men Cheng-fu of treating threatened abortion by using modified Shoutaiwan. It is argued that the kidney deficiency, blood deficiency was the basic pathogenesis of this disease, and syndrome of yin deficiency, blood heat and fluid deficiency often appeared in the disease. Modified Shoutaiwan was the basic remedy in treating this disease based on syndrome differentiation which was divided into kidney deficiency type and yin deficiency with blood heat type. A verification case is attached.