Objective To explore weekly levels of serum CA125, P and β-HCG in pregnant women of 4-12 weeks and their relations with threatened abortion. Methods A total of 270 pregnant women with threatened abortion who received pregnancy test in our hospital were selected as research subjects in this study, and they were in threatened abortion group. 30 healthy pregnant women who received pregnancy test in our hospital during the same period of time were se-lected as research controls, and they were in normal pregnancy group. All pregnant women had a gestational age of 4-12 weeks; the two groups of patients were all given chemiluminescence immunoassay to dynamically monitor the levels of serum CA125, P and β-HCG. Changes of serum CA125, P and β-HCG levels in the two groups of pregnant women were observed, analyzed and compared. Results CA125 level in the normal pregnancy group was significantly lower than that in the threatened abortion group, and the difference was statistically significant(P<0.05). Levels of P and β-HCG in the normal pregnancy group were both significantly higher than those in the threatened abortion group, and the differences were statistically significant (P<0.05). Conclusion Serum CA125, P and β-HCG in the prediction and early diagnosis of threatened abortion have significant clinical values, which are worthy of attention and promotion.