  We present a practical classification scheme for the four-partite entangled
states under stochastic local operations and classical communication (SLOCC).
By transforming a four-partite state into a triple-state set composed of two
tripartite and one bipartite states, the entanglement classification is reduced
to the classification of tripartite and bipartite entanglements. This reduction
method has the merit of involving only the linear constrains, and meanwhile
providing an insight into the entanglement character of the subsystems.
