Objective To investigate the values of nucleoprotein transformation in sperm for predicting recurrent abortion.Methods A total of 521 infertile couples with complete test indicators on fertility were selected from the reproductive medical clinic of our hospital from 2019 to 2022,among which the ages of the male were from 23 to 56 years old.The following factors causing recurrent abortion were excluded,including the age of woman,body mass index,metabolic disease,antiphospholipid syndrome,uterine and accessory abnormalities,history of caesarean section and intrauterine myoma/cervical conectomy,peripheral blood chromosome abnormalities of both the couple,and adverse life history,such as smoking/alcohol abuse.According to the abortion situation,they were divided into the recurrent abortion group(≥two spontaneous abortions),one spontaneous abortion group and no abortion group.Tukey's multiple comparison was performed to compare the differences of nucleoprotein transformation of sperm in each group by using GraphPad6.0 sta-tistical software.The Pearson method was used to analyze the correlation between nucleoprotein transformation and recurrent abortion.The predictive values of nucleoprotein transformation in recurrent abortion were analyzed by the parameters of sensitivity,specificity,positive predictive value,negative predictive value,Youden index and odd ratio.Results The percentages of abnormal nucleoprotein transformation in recurrent abortion group[(33.31±13.83)％]were significantly higher than those in non-abortion group[(26.85± 15.38)％]and the one abortion group[(28.20±12.50)％,P＜0.05].Pearson correlation analysis showed that there was a significant positive correlation between abnormal nucleoprotein transformation and recurrent abortion.The sensitivity and specificity of nucleoprote-in transformation for predicting recurrent abortion were 45.24％and 73.64％,respectively.All of the data of positive predictive value(15.70％),negative predictive value(92.53％),Youden index(18.88％)and odd ratio(2.31)of nucleoprotein transformation in predicting recurrent abortion were higher than those of high DNA stainability(10.64％,90.31％,1.05％and 1.11).Conclusion In the spouses of patients with recurrent abortion,the immaturity of sperm nuclear protein is significantly increased and significantly posi-tively correlated with recurrent abortion.The abnormal nucleoprotein transformation of sperm may be the important factor of recurrent a-bortion in males,and it has high predictive value for recurrent spontaneous abortion in clinical practice.