Background: Accumulating research suggests that hematopoiesis and bone metabolism are interconnected. Several studies have investigated the partial indexes of peripheral blood counts related to bone mineral density (BMD). The aim of this study was to investigate the associations between all of the parameters, especially the risk interval of complete blood counts (CBC) and BMD in a sample of elderly subjects aged >70 years. Methods: Three hundred and eighty-six subjects aged > 70 years in our hospital were enrolled in a cross-sectional study and underwent BMD measurement along with a CBC test. Patients were divided into two groups: "at least osteopenia" (T-score < -1) and a normal group (T-score >= -1). The clinicopathological characteristics, CBC parameters, and BMD were analyzed between the two groups. We performed a supervised discretization (using a conditional inference tree algorithm) to find the risk interval for the continuous variables, especially for CBC parameters, and bootstrap multivariable logistic regression to estimate the odds of CBC parameters associated with BMD. Results: A total of 248 subjects were included in the study and divided into the normal (n = 43) and "at least osteopenia" groups (n = 205). Subjects in the " at least osteopenia" group had varying degrees of decreases in white blood cell (WBC) count, red blood cell (RBC) count, hemoglobin (Hb), mean corpuscular hemoglobin concentration (MCHC), hematocrit ( HCT), platelet volume distribution width (PDW) mean platelet volume (MPV), eosinophils, and lymphocytes, and had increases in platelets (PLTs). MCHC, WBC, RBC, PDW, MPV, Hb, and lymphocytes were successfully divided into two (low and high) intervals. Bootstrap logistic regression showed that low levels of body mass index (BMI) [(11.88, 23.53); OR: 4.07; p < 0.0001], lymphocytes [(0.54, 2.3); OR: 3.95; p < 0.0001] and PDW [(8.5, 12.7); OR: 2.44; p < 0.0001] along with being female and older age [(72, 97); OR: 2.16; p < 0.0001] were significantly associated with BMD as risk factors. Conclusions: The elderly with BMD loss tended to show an abnormal sign in the CBC test. Low levels of lymphocytes and PDW may contribute to the evaluation of osteoporosis risk in the elderly. Bone remodeling and hematopoiesis may have stronger associations and interactions than has been previously recognized.