Research hypothesis:Compare the differences between the Experimental group and the Control group in bile duct injury rate,complication rate,blood loss,operative time ,conversion rate and hospital stay.It is supposed that the results of Experimental group are superior to the control group,difference is statistically significant(P<0.05). So the investigators can draw the conclusion that the anatomy method with the guide of right portal pedicle and Rouviere's sulcus is useful in laparoscopic cholecystectomy.