Abstract: In this paper the theoretical possibility of raising the minimum measured diameter among assets verification for natural unevenaged forest was discussed through extension coexist degrees and linear constraints method. The result showed that there was the possibility of raising the minimum measured diameter under this condition that average error of stock volume was sufficiently ensured as small as possible. And the reality of raising the minimum measured diameter for natural unevenaged forest was confirmed, because of its diameter distribution characteristics, by using rich plot data.