Herpes Zoster(HZ) is a common clinical disease, which is paid much attentions because of its severe PHN（Post-herpetic Neuralgia，PHN）. Surgery is one of important reasons for inducing HZ, which is more common in organ transplantation, spine surgery and trigeminal nerve surgery, and it is rare to have HZ after joint replacement. The paper reported a case of severe HZ after knee joint replacement for osteoarthritis: The patient is a 73-year-old male. He was diagnosed as osteoarthritis of both knees and underwent left total knee replacement. Four weeks after the operation, several scattered red rashes appeared on the upper left leg without obvious pain or itching, followed by herpes, which quickly spread to the whole medial leg, diffuse large amounts of herpes, and flushing around the herpes. He was diagnosed with herpes zoster. After 3 weeks of combined treatment with antivirus and improved neuronutrition, the herpes subsided. After 31 months of follow-up, there was no recurrence of herpes, no obvious pain, joint function was normal, and the artificial joint was normal. HZ after knee replacement is rare with atypical early clinical manifestations and difficult diagnosis, which can easily lead to misdiagnosis or missed diagnosis. The etiology, epidemiology, and features of early lesions of HZ should be better understood, as well as the clinical features of HZ after joint replacement. The diagnosis of HZ should be considered when unexplained skin burning pain, hypersensitivity or local rash occurs without obvious itching and other allergic manifestations. Observe the changes of local skin lesions closely and assist serological examination if necessary. It is conducive to early diagnosis and early treatment, so as to control symptoms as soon as possible, to shorten the course of treatment, to reduce the occurrence of PNH, and to prevent and cure complications.