Abstract: of age on ageing phenotype and whether there is a common factor or as-yet-unknown true cause representing shared variance for ageing phenotype.MethodsA total of 2 006 Qingdao residents aged 50-74 years participated the survey in 2009.Individual's self-rated health(SRH),hand grip strength,5 sit-to-stand test time(STS-5),forced expiratory volumes in 1 second(FEV₁),force vital capacity(FVC),near visual acuity,number of teeth lost,hearing threshold,cognitive function,and depression were measured.Structural equation model(SEM)was fitted by using Amos 7.0 software to explore the latent common factor for the ageing phenotypes.Results With the increase of age,SRH(β=-0.013),grip strength(β=-0.369),FEV₁(β=-0.025),FVC(β=-0.023),near visual acuity(β=-0.005),and cognitive function(β=-0.016)declined(P<0.001 for all),while STS-5 time(β=0.130),number of teeth lost(β=0.290),hearing threshold(β=0.516),and depression(β=0.123)increased(P<0.001 for all).SEM analysis supported a latent common factor protecting ten phenotypes(|β|=0.012-5.513,P<0.05)except hearing threshold(P=0.161).ConclusionAll the ageing phenotypes being measured declined obviously with the increase of age.There is a latent common protective mechanism underlying the human healthy ageing.