Objective To systematically evaluate risk factors associated with trismus in patients with head and neck cancer and to provide references for developing targeted interventions.Methods A comprehensive literature search was conducted in PubMed, Web of Science, Embase, Cochrane Library, CINAHL, SinoMed, CNKI, VIP, and Wanfang Data from inception to December 2024.Studies reporting factors influencing trismus in patients with head and neck cancer were included.Two researchers independently screened the literature, assessed the quality of the included literature, and extracted data.Meta-analysis was performed using Stata 14 software.Results Eleven studies involving 3,236 patients were included.Meta-analysis revealed that education level, tumor stage, tumor location, oral mucositis and dermatitis, adherence to functional exercises, baseline range of maximal mouth opening, and treatment modality (radiotherapy or adjuvant radiotherapy) were major influencing factors of trismus in patients with head and neck cancer.Conclusion The factors influencing trismus in patients with head and neck cancer are complex and diverse.Nursing staff should implement precise interventions based on accurate assessments to prevent the occurrence of trismus.