Abstract: There is a quantitative relationship between damage and acoustic emission in wood. Based on damagetheory and the acoustic emission signal in wood with defects and cracks indifferent damage phases, this paper establishes wood mechanics models ofdamage evolution under alternating load and static load,as two kinds of common situations. Analytical results agreewith lumber's actual situation. With specialcharacteristics of the acoustic emission, wood mechanics model of damageevolution with is established, which can be used to forecast thedamage in advance, and it is shown thatinhomogeneity is one of the main causes of damage.