This paper is concerned with a study of the deformation mechanism of a flat-topped, grid- domed textile composite possessing high specific energy absorption capacity. The composite was fabricated by curing thermoset resin-impregnated nylon knitted fabric as a grid-domed cellular structure. During the forming process the fabric stretching may affect the cell wall thickness which is a critical factor on the deformation mode and the global energy absorption capacity. The deformation mechanism of a unit cell was studied under quasi- static axial compression and a modified mechanics model is proposed to describe the large plastic deformation mechanism of the flat-topped, conical cell under axial compression. The potential applications of this textile composite include use as a shock-absorbing liner of bicycle helmets, an energy-absorbing vehicle door or other lightweight devices in which high energy absorption capacity is of great importance.