Resumo. The work study the relationship of density and diameter in Pinus taeda L. stand aiming to determining the diagram density management and describe the average-diameter trajectory in different management regimen with biologic and economic repercussion. For that, experimental growth-data measured periodically until 18 years was used. Results demonstrated that the Tang model of density and diameter predicts the maximum line efficiently, using to delimit the concurrence zone that predicted the average diameter among different population densities, as well as determine the objective diameter of the optimal management regimen to conduce the stand. The economic analysis showed a maximum present net value of 15.587,60 R$/ha and 708,50 R$/ha.year at management regimen with three thinning at 9, 13 and 18 years and final cut at 22 years. The comparison of the management regimen after equal-horizons of plan in 28 years, showed the same management regimen with the maximum economic efficiency with annual equivalent value of 1.253,40 R$/ha.year and a maximum internal rate of 14,83 % per year.