This experiment is using a method of photoelastic stress analysis to analyse tibia- astragalusload bearing region, size and tibia - astragalus joint contact stress distribution situation when theankle joint at different nexangle. The results show: when the flex angle is at 7° the contact streedistiribution is largest and the press stress is the smallest with even disribution if the angle enlangto over 19°, the contact stress distribution area will be decreased and press stress will be increased.When the flex angle is over 43°, the contest stress distribution area will be decreasd significantlywhile the press stress will be increased. Basing on these propositionwe we understand, in view ofstress, when one wears high heel shoes, the best flex angle is 0°19°, If the flex is over 43°,theankle joint tends to get tatigue injury.