A support slide assembly for a cable management arm is coupled with two slide assemblies. Two ends of the cable management arm are connected to one of the two slide assemblies. The support slide assembly includes a sliding member provided between the two ends of the cable management arm and sustained by the support slide assembly to travel in relation to the support slide assembly. Two ends of the support slide assembly respectively connected to the two slide assemblies. The support slide assembly includes a first rod and a second rod sliding into each other to become one retractable piece, allowing change of its total length. The two rods of the support slide assembly each is pivoted to a sliding block.