The invention discloses a single-suspension-arm front suspension system of an all-terrain vehicle for children. The system comprises front wheels, knuckles, single-rocker assemblies and dampers. One end of each single-rocker assembly is movably connected with a frame while the other end of each single-rocker assembly is hinged to the corresponding knuckle, the knuckles are fixedly connected with the front wheels, and the upper portion of each single-rocker assembly is fixedly connected with the corresponding damper. Each single-rocker assembly comprises a first rocker pipe, a second rocker pipe, a vertical column pipe and rocker sleeves, wherein an assembly end of the first rocker pipe and an assembly end of the second rocker pipe are fixedly assembled through the vertical column pipe, andbranch ends of the first rocker pipe and the second rocker pipe are provided with the rocker sleeves respectively. By adoption of the single-suspension-arm front suspension system, the all-terrain vehicle for children is capable of stably and safely turning and effectively prevented from rolling over, vibration and impact in running of the all-terrain vehicle are greatly reduced, an advancing direction of the all-terrain vehicle can be controlled flexibly and accurately, stability and comfort in turning are improved, and stability and safety of the all-terrain vehicle for children are guaranteed.