Abstract: Objective We studied the blood pressure heritability and wave trend of the different period of time through sib pairs datum.Methods A large scale investigation of blood pressure was taken.The information of the sib pairs was collected and all kinds of enviromental factors and occupational exposure were analysed.The blood pressure for different period of time was measured by the mer cury column blood-pressure meter.Results The heritability of blood pressure value was analysed by the classic Holziger method,and the BP heritability of the different period of time was distinctive.The heritability of SBP in the noon was the highest (0.97)and one of DBP was the greatest in the afternoon.The regression of SBP by sex showed the same wave trend,the lowest in the morning,elevated in the forenoon and reached the highest point in the afternoon,declined in the evening.Conclusion The blood pressure heritability in the different period of time was distinctive.