Psoriasis is an immune-mediated systemic disease with multiple organs involvement, such as cardiovascular, live, gut, endocrine, and so on. Bullous pemphigoid (BP) is a rare comorbidity associated with psoriasis, while BP occurring in erythrodermic psoriasis (EP) is very rare. In this case, we reported a woman with severe EP who developed BP, in whom beta hemolytic streptococcus infection was a possible triggering factor. The complicated condition of such patients needs to draw attention of the physician and study further for better treatment.