Objective To study the anatomy of facial recess(FR) and the relationship between the position of FR and the round window niche(RWN) in children who need cochlear implant by high resolution temporal bone CT.   Methods Seventy-eight children (154 ears) with cochlear implant were analyzed with preoperative high-resolution temporal bone CT. The following parameters were measured at the RWN level of axial CT scan: 1. The distance between the facial nerve(FN) and the posterior wall of the external auditory canal (d1); 2. The distance between FN and RWN (d2); 3. The relative angle between FN and RWN (a); 4. The distance between the midpoint of FR and RWN (d3); 5. The relative angle between the midpoint of FR and RWN (b). The factors that might affect the anatomy of FR were recorded, including sex, age, and the anatomical variation on HRCT (such as the type of mastoid gasification, the position of sigmoid sinus and jugular bulb, the expansion of vestibular aqueduct). The correlation between the above factors and the measurements of FR was analyzed.   Results The distance d1 was (4.21±0.69) mm, the distance d2 was (5.95±0.62) mm, the angle a was (94.61±9.04)°, the distance d3 was (6.46±0.63) mm, the angle b was (113.47±7.83)°. The width of FR (d1) was affected by three factors: age, gender and anteversion of sigmoid sinus. The angle a and the angle b were affected by expansion of vestibular aqueduct.   Conclusion High resolution CT of temporal bone before cochlear implantation can show the important anatomical relationship of FR, and the measurements can be of clinical reference value for cochlear implant surgery.