Pregnancy and lactation-associated osteoporosis (PLO) is a rare but serious and difficult to be diagnosed disease, which occurs in the late gestation and early lactation, mainly manifested by low back pain, vertebral fracture and reduction of hip bone density. It is difficult to diagnose and has a high rate of misdiagnosis and mistreatment. We present the case of a 39-year-old woman who suffered from acute low back pain and walking difficulty after a sudden stoop in 2 months postnatal. The X-ray and MRI examination showed that fractures occurred in the first, second and fifth lumbar vertebrae. Bone mineral density (BMD) examination confirmed osteoporosis. After stopping lactation, calcium and vitamin K2 supplemented, compared with zoledronic acid injection, the low back pain was relieved and the BMD increased gradually. The incidence of PLO is seriously underestimated in clinical practice. Women in pregnancy and lactation with acute low back pain should be highly alert to the occurrence of PLO, and early treatment need to be taken in case of further serious consequences such as vertebral compression fracture or hip fracture.