1) death. This crab dead can not eat, will have diarrhea, so be sure to pick live to buy. Buy back always have to wash it, then you have to first death. My method is to insert a chopstick directly into the crab's mouth, and soon they will not flap their teeth and claws.
2) Wash and brush. Get a toothbrush and scrub around, there's not much to it.
3) At this point, you have two choices: throw the whole crab in the pot and boil it: or get back to work.
I usually choose the latter. I don't want too many nasty things cooking in the pot because I'm making soup. So, first, cut off the back cover of the crab.
Then peel off the crab's shell, remove the black stripes near the back cover (still poop); remove the gills on both sides of the body (those white conical spongy objects) where there is a lot of filth, and then brush and rinse. Finally, remove the sand sacs on the crab cover near the mouth. I personally think this step is very important, one can avoid the sand sacs broken leak out a bunch of sand, and secondly, according to Chinese medicine, this thing is extremely cold, is not good for the body.
When the crab breaks the air is ready to do the other supporting work.