Abstract: Study on the variation of seed yeelds in clone seed orchards of masson pine, the results indicates that the variation source from the differences of clones、site type and interaction of clones environmental which are very significant. Orchard site slope orientation and density also affect the seed yieeds very obviously. Choosing clones of high seed production, correct site locaton and required in the middle and late stage of the growth in the orchards the most effective measure for increasing seed yields in seed orchards.