The purposes of the study were to estimate the incidence of metabolic syndrome (MetS) and to systematically evaluate the relationship between hematological parameters and MetS in a 5-year follow-up of Beijing adult population. The longitudinal study included 3,180 adults, aged 20-65 years, who attended health check-ups in Beijing Tongren Hospital in 2007 and 2012. Multivariate logistic regression was conducted to explore the associations between hematological parameters and MetS. The 5-year cumulative incidence of MetS in this sample was 10.82 % (14.22 % for males and 7.59 % for females). Among all the hematological parameters, white blood cell count (WBC) was positively associated with MetS for 20-35-year-old (male OR 1.482, 95 % CI 1.169-2.974; female OR 1.398, 95 % CI 1.145-3.011), and 36-50-year-old (male OR 2.012, 95 % CI 1.290-4.010; female OR 3.400, 95 % CI 1.818-4.528) male and female subjects. Alanine aminotransferase (ALT) was significantly associated with the incidence of MetS for males (20-35-year-old OR 2.080, 95 % CI 1.371-3.159; 36-50-year-old OR 2.421, 95 % CI 1.335-3.412; 51-65-year-old OR 4.267, 95 % CI 1.161-6.781). Low-density lipoprotein cholesterol (LDL-C) was positively associated with MetS for 51-65-year-old (male OR 3.078, 95 % CI 2.468-5.131; female OR 2.140, 95 % CI 1.524-4.359) for male and female subjects. WBC is positively associated with MetS for young adults, while LDL-C is positively associated with MetS for elderly people. ALT is positively associated with MetS for males. Our findings provide further evidence in support of using hematological markers for early detection of individuals at risk for MetS.