Objective: To screen and optimize the operation standard of ankle pump in children with lower extremities central venous catheter (CVC). Methods: A total of 92 children with lower extremities CVC were included in this study, who were treated at our hospital from January 2018 to December 2019. All the children were randomly divided into four groups with 23 cases in each group, and given ankle pump exercise with different rhythms. Group A: plantar flexion 2 s, dorsiflexion 2 s; group B: plantar flexion 3 s, dorsiflexion 3 s; group C: plantar flexion 4 s, dorsiflexion 4 s; group D: plantar flexion 5 s, dorsiflexion 5 s. Effects of ankle pump exercise with different rhythms on the occurrence of CVC-related complications in children [including the incidence of deep vein thrombosis (DVT)], femoral vein vessel diameter, blood flow peak velocity and the incidence of limb swelling were compared. Results: Different rhythms had no significant effect on CVC related complications (P>0.05), while had different effects on the diameter and peak velocity of femoral vein in children. Among them, ankle pump rhythms with 5 s for plantar flexion and 5 s for dorsal extension could significantly expand the diameter of femoral vein and increase the peak velocity of femoral vein blood flow (P<0.05). In addition, ankle pump exercise with 5 s for plantar flexion and 5 s for dorsal extension could significantly reduce the incidence of limb swelling (P<0.05). Conclusion: The rhythm of 5 s for plantar flexion and 5 s for dorsal extensionis the best rhythms for ankle pump exercise in children with CVC catheterization, which can effectively dilate veins, increase blood flow velocity and reduce the incidence of limb swelling.