Objective To compare the effects of visual rigid laryngoscope and visual laryngoscope in nasotracheal intubation(NTI)for patients with cervical spine immobilization simulated difficult airway.Methods Ninety patients scheduled for selective surgery under general anesthesia requiring NTI,52 males and 38 females,aged 18-64 years,BMI 18.5-25.0 kg/m2,ASA physical status Ⅰ or Ⅱ,were scheduled for selective surgery under general anesthesia requiring NTI.Before anesthesia induction,the spinal surgeon selected an appropriate cervical collar and adjusted it to fix patient's neck to establishing difficult airway sim-ulation model.All patients were randomly assigned into two groups:visual rigid laryngoscope(group R)and common visual laryngoscope(group C),45 patients in each group.NTI was performed using either visual rigid laryngoscope or visual laryngoscope in groups R and C,respectively.The nasal passage time,glottic exposure time,intubation time,number of successful first intubation attempts,and intubation attempts were recorded.Glottic exposure was assessed using the Cormack-Lehane(C-L)grading system,and the intuba-tion condition was quantitatively evaluated using the modified nasal intubation difficulty scale(NIDS).The blood pressure and heart rate were measured at baseline(T1),immediately after intubation(T2),and at 1 minute(T3)and 3 minutes(T4)after intubation.The occurrence of intubation-related complications(nasal bleeding,sore throat,hoarseness)was recorded.Results Compared with group C,the nasal passage time and proportion of successful intubations without difficulty were significantly increased in group R,and the glottic exposure time and intubation time were significantly decreased in group R(P<0.05).Compared with group C,the HR and MAP at T2 and T3 were significantly decreased in group R(P<0.05).Com-pared with group C,group R had significantly lower incidence rates of nasal bleeding,sore throat,and hoarseness(P<0.05).There were no statistically significant differences in the first intubation success rate,number of intubation attempts,or C-L grade between the two groups.Conclusion Patients with cer-vical spine immobilization simulated difficult airway,both visual rigid laryngoscope and visual laryngoscope can be performed safely and effectively in NTI.Compared with visual laryngoscope,visual rigid laryngoscope can provide faster glottic exposure,shorter intubation time,lower intubation difficulty,less hemodynamic impact,and lower incidence of complications.