Fixing base for a child car seat

The base has a sliding platform moving in translation relative to a main casing (10) between two positions. A ring (60) is mounted to freely rotate on the platform about an axis (A-A). An attachment support (70) and locking hooks (72) are rigidly connected to rotate with the ring for attaching a seat. A connecting rod (80) has ends respectively connected with the casing and the ring, and configured such that the translatable movement of the platform rotates the ring. An elongated shaped protection plate (50) is fixed below the support and is not rotatably connected to the support.