[Objective] The dynamic variation of net primary productivity of Pinus tabulaeformis forest in Shanxi Province was studied

and the potential for improvement of plantation forest was predicted to provide reference for improving quality of regional forest.[Methods] The regression equation was established using the stratification and harvesting method and the relative growth model. Cumulative method and Thornthwaite Memorial model were used to estimate the actual and potential productivity of the forest.[Results] The productivity of P. tabulaeformis forest increased with the increase of its age and decreased when it evolved into mature period. The actual productivity of P. tabulaeformis forest was 4.462 t/(hm2·a); The contribution of trees was 72.17% to the total productivity at young stand. With the increase of age

total biomass got increase

but in the sense of productivity

it got decrease when evolved into late near-mature period. The contribution of herb layer was 21.16% in the young forest stage

and decreased latterly. On the contrary

the contribution rate of shrub layer increased gradually

which was more than that of the herb layer in the early mature period

when it is critical for structural management. The average potential productivity of forest was 8.422 t/(hm2·a)

implied that there was at least 32% potential room for improvement.[Conclusion] The potential room of P. tabulaeformis productivity was at least 32%

and the primary limiting factor of P. tabulaeformis forest productivity in Shanxi Province was rainfall.