Objective: To explore the median effective dosage (ED50) of etomidate for gastroscopy in elderly people when combined with oxycodone. Methods: Twenty-nine elderly people underwent gastroscopy in the First Center Hospital of Baoding from June 2017 to January 2018 were included in this study. Those patients, aged 65 to 78 years, weighing 49–66 kg, with American Society of Anesthesiologists physical status I–III, were intravenously injected with oxycodone 0.05 mg/kg. After 2 min, all people were intravenously injected with etomidate. Gastroscopy was performed when the eyelash reflex disappeared. The dose of etomidate was determined by sequential method, and initial dose of etomidate was 0.2 mg/kg. The next patient used a higher level of dosage when the last patient had a cough or somatic reaction during gastroscopy, and the ratio of adjacent dosage was 1:1.2. The ED50 and 95% CI of etomidate were calculated by probability unit method. Results: The ED50 and 95% CI of etomidate for gastroscopy was 0.15 mg/kg (95% CI 0.13–0.17 mg/kg) in elderly people when combined with oxycodone. Conclusion: The ED50 of etomidate for gastroscopy was 0.15 mg/kg in elderly people when combined with oxycodone.