Objective The incidence of deep neck infection (DNI) has been increasing in recent years. Sometimes, the treatment of DNI is intractable. This study aims to improve the clinician's understanding of this disease and the choice of treatment through the analysis of difficult cases with DNI.Methods Clinical data of 7 patients with severe and complex deep neck space infection admitted to our hospital from January 2018 to June 2022 were analyzed retrospectively.Results The 7 patients included 5 males and 2 females. Their age ranged from 40 to 72 years old, with an average age of 56.86 and 5 were over 50. Diabetes mellitus (4 cases) was the most common comorbidities. The most frequently involved neck space was the parapharyngeal space (6 cases), followed by the submandibular space (5 cases) and the pretracheal space (5 cases). All patients were managed with surgical treatment and antibiotics. Five cases underwent lateral cervical incision and drainage with combining cervicothoracic incision and drainage in 2, 1 underwent intraoral incision and drainage, 1 received percutaneous mediastinal puncture drainage.Tracheotomy was performed in one case. All the patients were cured. The most common complication was hypoproteinemia (4 cases), followed by descending necrotizing mediastinitis (3 cases).Conclusions Complicated deep neck space infection tends to occur in elderly men and patients with diabetes. Early diagnosis and prompt treatment play critical roles in reducing serious complications. Individualized treatment strategy can help to shorten the course of infection in different space.