When constructing differential equations for the tracked vehicles on the nonholcinomic constraint condition, the complex calculation problems tend to be caused. For such problems, this paper proposes a modeling method that simplifies the tracked vehicle as single and multi-body model based on the holonomic constraint condition on the given slope path. System rolling resistance and the dissipated force caused by the loss of electromotor torsion are deduced by mechanical analysis for the vehicle. Then system energy is calculated by combining the holonomic constraint condition with the model of monomer lumped mass and the model of multi-body. Finally system equation of motion is established by Lagrange equation and motion model is gotten. In addition, the feasibility of the model is verified by a calculation example, which offers a, theoretical reference for tracked vehicles traveling on slope road surface.