Objective To explore the effect of general anesthesia on Wuzhishan miniature pigs induced by a mixture of ketamine, Sumianxin II and midazolam, and maintained by ketamine and propofol in surgery lasting up to 8 hours. Methods A total of 18 Wuzhishan miniature pigs (body weight (20.3 ± 1.9) kg, 14 male and 4 female) were used in this study. The induction of anesthesia was performed with intramuscular injection of ketamine (8 - 10 mg/ kg) Sumianxin II (1.5 mL) and midazolam (10 mg) behind the ear, and the general anesthesia was maintained with a mixture containing 0.9% sodium chloride 8 mL, ketamine 100 mg/2 mL and propofol 200 mg/40 mL, continuously injected through the marginal ear vein through a syringe infusion pump. The time spent for anesthesia induction and the duration time of anesthesia were recorded. Physiological indexes including body temperature, blood pressure, heart rate and respiratory rate, the reflex activities, and the effects of analgesia, sedation and muscular relaxation of the miniature pigs under anesthesia at 0, 0.5, 1, 1. 5, 2, 4, 6, 8 h were observed. Results All the 18 pigs were successfully anaesthetized, but 4 pigs died during surgery due to hypovolemic shock, anesthesia accident, left main coronary thrombosis and reperfusion arrhythmia, respectively. During anesthesia, the analgesia, sedation and muscular relaxation effects on the pigs were obvious. The average time spent for anesthesia induction was (4.8 ± 1.2) min and the duration time of anesthesia was (54.1 ±5.8) min. The eyelid reflex, corneal reflex and anal reflex in the pigs were weak or disappeared during 1 - 8 h after the anesthesia was induced. The body temperature of the pigs was decreased gradually, with a significant difference between 1 h and 0 h (P < 0.05), reaching the lowest point at 4 h, and then maintained stable. The blood pressure was gradually decreased, reaching the lowest level at 2 h (P < 0.05), then somehow increased, and maintained at a stable level until the end of surgery. The respiratory rate fluctuated during the anesthesia, with no significant difference. Conclusions The anesthesia induced by a combination of ketamine, Sumianxin II and midazolam and maintained with a combination of ketamine and propofol is simple to operate, shows effects fast, and has good effects of analgesia, sedation and muscular relaxation, keeping the circulatory system and respiratory system relatively stable throughout the anesthesia. Thus it is suitable for general anesthesia for miniature pigs.