The caliper logging tool is a downhole tool to measure the diameter of wellbore, and the domestic open hole measurement tools are mainly threearm and fourarm caliper. The split sixarm caliper log tool was designed using Pro/E, its motion states were analyzed, and concluded that there were two kinds of motion states: opening and measuring. The mathematical model of the two states of the split push system was established, and the motion characteristic analysis was performed by the closed vector polygon projection method. Structural parametric design and cam motion characteristics analysis of Archimedes spiral push arm in splitting pushing system were carried out. Using Adams software to perform parameterized modeling and motion simulation of the opening and measurement state, the trajectory curves of the push arm and the piston rod were obtained. The movement law and state of the mechanism are verified, which is the followup two Suboptimization provided as a valid reference.