Abstract: Objective To understand the prevalence and influencing factors of prehypertension in middle-aged Chinese. Methods The study used the data from China Health and Retirement Longitudinal Survey（CHARLS）in2015 to investigate the basic information such as blood pressure,waist circumference,height and weight,and health behaviors in 7178 middle-aged adults aged 45-59 years. Prehypertension was defined as systolic blood pressure（SBP）≥120 and≤139 mm Hg and/or diastolic blood pressure（DBP）≥80 and ≤89 mm Hg;and the history of hypertension or taking antihypertensive drugs was excluded. Results The detection rate of prehypertension was45.2%in the middle-aged people,which was higher in the male（48.3%）than that in the female（42.6%）. The detection rate of prehypertension was increased with age in women（P＜0.01）,while that was relatively stable in men.Multivariate regression analysis showed that underweight（OR=0.264,95% CI 0.075-0.929）was a protective factor and abdominal obesity（OR=1.554,95% CI 1.027-2.350）,overweight（OR=1.734,95% CI 1.139-2.640）and obesity（OR=2.350,95% CI1.266-4.363）were risk factors for prehypertension in men;while underweight（OR=0.509,95%CI0.280-0.926）was a protective factor and 55-59 years old（OR=1.553,95%CI1.227-1.966）and obesity（OR=2.655,95% CI1.976-3.568）were risk factors for prehypertension in women.Conclusion The detection rate of prehypertension in middle-aged Chinese people was high. Overweight,obesity and abdominal obesity were risk factors for prehypertension in the male,while 55-59 years old and obesity were risk factors for prehypertension in the female.