Abstract:The differences of moisture content in the wood of living trees of the three locality types of 1arch forest have been found． Moisture content in the wood of larch-broad-leaves mixed forest is the highest (155.03％，in sapwood)；while that of the larch-maple．Forest the medium(124.19％，in sapwood)，and that of the sphagnum high moor larch forest the lowest(120.72％，in sapwood)．The less moisture found in the wood of the a sphagnum high moor larch forest is closely related to the excessive water content in the soil of this locality type of larch forest． The vertical distribution of moisture is different in the three locality types of larch forest．In the sphagnum high moor larch forest，the moisture content of stems is 117.13％ at base，then gradually decreases to 78.27％from the base upward to height of 3.3m.，and then increases to the highest of 156.4l％at the top．In the larch-broad-leaves mixed forest， the moisture content of stems is 101.19％at base which is the highest，then decreases to 79.57％from the base upward to height of 15.3 m.，and then increases again．In the larch-maple-forest，the moisture content of stems is the highest at base，then graduaUy decreases．But at 9.3-15.3 m．Increases again． The lateral distribdon of moisture is probably the same in the three locality types of larch forest． It decreases gradually from the pith outward．But increases after 50-100 growth rings，and attains the highest near the bark． In the three locality types of larch forest，the moisture of the sapwood is usually higher than that in the innermost part (around pith)and heartwood．The higher moisture content in innermost part of wood is closely related With the structure of wood． No noticeable variation of the moisture content in the four directions of the cross section is found at all．The variama depend’s on the extensible area of crown cover in different direction． The moisture content of fresh leaves is different in the three locality types of larch forest． It varies with the different positions of the crown． According to the vertical and lateral distribution of moisture in wood of living trees， the speed of water conduction is: fast in the vertical direction，less so in tangential direc- tion，and slow in radial direction． The wood checking is probably owing to the speed of water movement and the uneven distribution of moisture along the radial direction． The dimension of trees has a great effect on the amount of the moisture．In general， difference in moisture content increases with the of height increment and the diameter increment．