Objective To explore the clinical significance of combined detection of serum levels of estradiol (E2), progesterone (Pro) and E2/p ratio and abdominal ultrasound on the diagnosis of early pregnant threatened abortion. Methods 85 cases of early pregnancy (5 to 12 weeks) which showed the threatened abortion symptom were divided into threatened abortion pregnancy group and threatened abortion pregnant failure group. 50 normal pregnancy cases with same pregnant weeks were selected as control group. The serum levels of E2 and Pro were determined by electrochemluminescence immunoassay. The patients were also carried abdominal ultrasound examination. Results The serum E2 levels and the ratio of E2/P in threatened abortion pregnancy group were significantly lower than the normal pregnancy group (P<0.05), but there was no statistically difference on the serum progesterone levels between two groups (P>0.05). Combined with color Doppler Ultrasound, the normal pregnancy group showed the gestational sac, yolk sac and embryo. However, there is 88.3% visible gestational sac, 76.7% visible yolk sac, and 50%visible germ in threatened abortion pregnancy group. Moreover, the serum levels of E2, Pro and the ratio of E2/P in threatened abortion pregnant failure group were lower than that of in the normal pregnancy group (P<0.05). The serum levels of E2, Pro and the ratio of E2/P in threatened abortion pregnancy group were obviously higher than that of threatened abortion pregnant failure group (P<0.05). Conclusion Combined detection of serum levels of estradiol, progesterone and E2/p ratio and abdominal ultrasound have an important clinical significance on the diagnosis of early pregnant threatened abortion.