We extend the concept of site percolation and bond percolation to multisite percolation in which each active element in the random process involves more than two sites. We show that the partition function of the Ising model with multisite interactions of strength Jm is the generating function of a multisite-correlated percolation model. From this connection, we conclude that the phase transition of the Ising model with multispin interactions is also a percolation transition. Based on such connection, we define nonpercolating geometrical factor gf and percolating geometrical factor gp which depend only on geometrical properties of the system. The thermal properties of the Ising model with multispin interactions may be derived simply from gf and gp. The theory is confirmed by an exact calculation for a one dimensional model with four-spin interactions.