There must be something of unusual qualities in Mark Twain s children protagonists, which distinguish his children s fiction from his other works.

Convention on the Rights of the Child has established common principle for protecting child rights and interests, international documents concerned also establish the legal rights of child witness in the criminal lawsuit, external criminal lawsuit legislation also formulate the system of child witness rights.

There are always lots of disputes on the competency to the child witness because of children s special physiology and psychology.

Child witness physical and psychological characteristic determines the defects in their memory information cding,storing,retrieval process,but it should not be the reason of negat-ing the child s competency as a witness.