The invention relates to a four-port feeding resonant cavity for wood microwave pretreatment, which comprises a horizontal cubic microwave cavity A, two vertical cubic microwave cavities B and C and two horizontal cubic microwave cavities D and E, wherein B and C are respectively connected with the upper and lower surfaces of A; an upper port of B and a lower port of C are openings; a left port of D and a right port of E are openings; front and back ports of A are openings; the horizontal width of A is equal to that of B and C; the vertical height of A is equal to that of D and E; and the scope of the vertical height of A is as follows: h is more than 0.08m but less than 0.11m. The four-port feeding resonant cavity can increase the uniformity of the temperature distribution of the wood microwave pretreatment and has important significances in the later impregnating treatment of wood and the preparation of novel high-performance material.