Breast cancer-related lymphedema is a treatment-related chronic disease that causes great distress and medical burden. Early screening and precautionary measures for lymphedema could improve well-being and decrease medical costs. Herein, we used bioelectrical impedance analysis for early screening of lymphedema. We set up a verifiable standardized subclinical standard to screen subclinical lymphedema in postoperative breast cancer patients using bioelectrical impedance. The first part determined the criteria of subclinical lymphedema. Among the 424 female participants, 127 were healthy women, whereas 297 were postoperative breast cancer survivors. Subclinical standard boundaries were determined by the 95% confidence interval of the healthy women. The screening rate of patients with subclinical lymphedema was inferred by comparing the subclinical standard boundaries and the postoperative patient values. A total of 14.81-20.87% of postoperative breast cancer survivors were identified as patients with subclinical lymphedema. The second part provided the results of the verification test of this subclinical standard. The data of the verification test from 30 healthy women and 30 screened patients met the subclinical standard, and 30 breast cancer survivors with lymphedema verified the utility and feasibility of the subclinical standard. Therefore, this standard could provide a screening tool for early the identification of subclinical breast cancer survivors. Early detection helps implement personal and precise medical precautions for patients with subclinical lymphedema.