During the duck egg brine immersing process,changes in salt content,egg weight,eggshell relative weight,eggshell thickness,pore number,chamber diameter,eggshell fragility and hardness per unit area and eggshell cross-section microstructure were studied.On the 5th weeks after salting,with the salt content increasing,the duck weight increased from 61.85g to 63.16g;eggshell weight,eggshell thickness had no significant changes;a slight change in chamber diameter;pore number was reduced from 24.93/0.25cm2 to 10.40/0.25cm2.Eggshell fragility and hardness per unit area was reduced from 445.2N and 1461.2N to 240.6N and 446.1N respectively.Egg force decreased from 4.538kgf to 3.513kgf.Duck eggshell relative weight was less than 10%.Eggshell thickness was less than 0.355mm.Egg shape index was between 1.380 and 1.460 which was in the low intensity range.The eggshell were very easily to crack.After 5th weeks of salting,there were some lines and irregular fault on eggshell cross-section.Cracked egg shell had rough cross-section with some irregular fracture,papillae arrangement was uneven,eggshell membrane was loosen.The conclusion is that duck eggshell crack is caused by quality of fresh duck eggshell,and the brine curing processing destroyed the shell microstructure and fragility,and hardnes.