Objective:To observe the effects of endocrine mechanism on uterine contraction on late pregnancy rats by applying acupuncture on KI6 using"open-close"needling time and"host-guest"needling sequence according to eight methods of the intelligent turtle.Methods:32 pregnant rats were divided into"open/host-guest"group(OHG group),"open/guest-host" group(OGH group),"close/host-guest"group(CHG group)and pregnant control group(PC group).8 healthy grown-up female rats were made into un-pregnant control group(UPC group).Firstly,open KI6 time was calculated.OHG group and OGH group were needled during the KI6 open time but CHG group was needled during the KI6 close time.Host-acupoint KI6 and guest-acupoint LU7 were needled for 5 minutes separately.After this,LI4 was needled for 20 minutes and then SP6 for 5 minutes.The contents of serum Estradiol(E2),Progesterone(P),ThromboxanceB 2(TXB 2)and 6-Keton-ProstaglandinF 1?(6-K-PGF 1?)were measured. Results:Compared with UPC group,the contents of serum P in OHG group increased significantly(P