Skin reaction or dermatological toxicities induced by immunotherapy is common. It usually manifests skin rash or erythema and can be cured by skin lotion or steroid. Nivolumab, a human IgG4 programmed cell death protein 1 (PD-1) inhibitor, blocks T cells activation preventing signal and allows the immune system to clear cancer cells. Nivolumab was approved in the second-line therapy in squamous cell lung cancer by FDA, with less than 10% unusual skin reaction, like sensory neuropathy, peeling skin, erythema multiforme, vitiligo, and psoriasis. Radiotherapy could aggravate this skin reaction through inflammatory response and promotion of immunity. The combined treatment of anti-PD-1 and radiotherapy represented a new promising therapeutic approach in many studies, but the risk of side effects may be high. We reported a patient with advanced squamous cell lung cancer who suffered from serious skin immune-related adverse events when he was treated with nivolumab and radiotherapy. The immune overreaction of the treatment of anti-PD-1 treatment and radiotherapy might cause these serious skin adverse events. Our report warranted careful workup to reduce the risk of side effects by combinative therapy with anti-PD-1 and radiotherapy.