Objective To provide anatomic data for operation of inserting the electron cochlear in young children. Methods Fourteen heads,28 sides specimens of young children of 1-to-5-year old were dissected,through posterior tympanum approach,via mastoidectomy,posterior tympanoto to enter posterior tympanum.The related anatomy structures of the location of the electron cochlear inserted into the proper sites were observed and measured under surgical microscope. Results The round window was seated in superior part of the round window niche.The pyramidal eminence,tendo musculi stapedius,incudostapedial joint,base of stapes,cochleariform process,round window niche and promontorium tympani were all visible from different directions.The posterior arch of stapes was situated in the prozone of scala.Scala was situated in the posteroinferior scala vestibuli.The distance from the middle point of the anterior border of the round window niche to the inferior wall was (149±0.42)mm,to the posterior wall of the Scala tympani (0.90±0.31)mm,to the basal tissue (149±0.41)mm,to the pyramidal eminence (328±0.55)mm,to the lateral semicircular canal (741±0.90)mm,to the inferior margin of the base of stapes (309±0.53)mm.Conclusion It is considered that the location of the insertion should be at the middle point of anterior border of the round window niche anterior from 0.90mm to 149