In this paper based on generalizing of two-mode squeezed operator, we construct a new three-mode squeezed operator. Further, the three-mode squeezed partical-number state is proposed by the technique of integration with an ordered product of operators. Its squeezing and antibunching effects are analyzed. The results indicate that its squeezing is weakened with the increase of photon number, and the antibunching effect of a1-mode field is also weakened with the increase of photon number; on the other hand, its a2-mode field and a3-mode field both exhibit antibunching effects.