SUMMARY
In this paper, the sectional curvature of non-degenerate tangent sections of time-like ruled surface with the central ruled surface in n-dimensional Minkowski space, R_1^n is studied. The relationship between normal sectional curvature and the principal sectional curvatures of non-degenerate tangent sections of time-like ruled surfaces is obtained andcalled as Lorentzian Beltrami-Euler formula. Moreover, the relationship between the Gaussian curvature and the principal distribution parameter of the non-degenerate tangent sections of time-like ruled surfaces is obtained and called as generalized Lorentzian Lamarle formula.