Abstract： Objective To investigate the effects of simulated heliox diving on the liver function of divers at different high altitudes.Methods In the dual-purpose hyperbaric and hypobaric chamber complex,4divers conducted a series of simulated dives at various altitudes and under different simulated environmental conditions:the 30 m dive at an altitude of 3000 m,the 30 m dive at an altitude of 4000 m,and the 30 m and 50 m dives at an altitude of 5 200 m.Blood samples were taken respectively at the following time points:on the morning of the first day of the experiment before they entered the chamber on an empty stomach ; on the morning of the third day of the experiment at an altitude of 3000 m also on an empty stomach; at 17:30 pm before supper on the fourth day of the experiment,when the divers were decompressed and returned to the surface at an altitude of 3 000 m,upon completion of the 30 m-dive; at 17:30 pm before supper on the sixth day,when the divers returned to the surface at an altitude of 4000 m,upon completion of the 30 m-dive; on the morning of the seventh day on an empty stomach,the divers stayed overnight at an altitude of 5200 m.The liver function indexes,including serum glutamic pyruvic transaminase,serum total bilirubin,serum direct bilirubin,γ-glutamyl transpeptidase,alkaline phosphatase,and serum albumin,were measured with biochemical autoanalyzer at 1th,3 rd,4th,6th,7th,8th,and 9th days respectively,and changes in liver function indexes before and after high altitude dives were analyzed.Results The above indexes detected at various time points both before and after the experiment were all within normal range,without statistical significance (P ＞ 0.05) Conclusions The simulated heliox diving at different high altitudes did not have obvious effects on the liver function of the divers.