The research of two-dimensional forest dynamics system model is still open.First

for the peculiarity of two-dimensional forest dynamics systems with initial state depending only on total quantity of forest

and boundary condition depending only on initial state again

boundary of system not satisfying one of 3 kinds common conditions

by introducing a class of special family curves in presence region of “stand agediameter”

the problem of boundary conditions is avoided. Secondly

using the technique of selecting measure dimension of lumber diameter properly

a wellposed two-dimensional forest dynamics system model is propounded. At last

colligating the technique of pulling characteristic curve

a prior -estimate

 structuring integral equation of initial state

iteration

the existence and uniqueness of the global classical solution are proved for this system.