In this paper, we study the initial-boundary value problem for the semilinear parabolic equations
u_{t} -△
_{X}u=|
u|
^{p-1}u, where
X=(
X_{1},
X_{2}, …,
X_{m}) is a system of real smooth vector fields which satisfy the H?rmander's condition, and
is a finitely degenerate elliptic operator. Using potential well method, we first prove the invariance of some sets and vacuum isolating of solutions. Finally, by the Galerkin method and the concavity method we show the global existence and blow-up in finite time of solutions with low initial energy or critical initial energy, and also we discuss the asymptotic behavior of the global solutions.