The study is being conducted to evaluate the efficacy, and safety of dexmedetomidine hydrochloride nasal spray for preoperative sedation in adults. To explore the reasonable dosage of dexmedetomidine hydrochloride nasal spray for preoperative sedation.

Inclusion Criteria:

1. Able and willing to provide a written informed consent
2. Subjects requiring elective general anesthesia surgery
3. Male or female
4. Meet the weight standard
5. Conform to the ASA Physical Status Classification

Exclusion Criteria:

1. Not suitable for nasal spray
2. Subjects who had received general anesthesia
3. Subjects with a history of myocardial infarction or unstable angina pectoris
4. Subjects with atrioventricular block or cardiac insufficiency
5. Subjects with a history of ischemic stroke or transient ischemic attack
6. Subjects with poor blood pressure control after medication
7. Subjects with abnormal clotting function
8. Subjects with a history of mental illness and a history of cognitive impairment epilepsy
9. Subjects with a history or possibility of a difficult airway
10. Subject with a history of substance abuse and drug abuse
11. Adrenoceptor agonists or antagonists were used before randomization
12. Abnormal values in the laboratory
13. Thyroid dysfunction
14. Allergic to a drug ingredient or component
15. Pregnant or nursing women
16. No birth control during the specified period of time
17. Participated in clinical trials of other drugs (received experimental drugs)
18. The inestigators determined that other conditions were inappropriate for participation in this clinical trial