Research of turbulence Rayleigh-Bénard convection with high Ra number is a hot topic in physics research in the world. DNS simulation is one of the important means to study the subject. The computing work is hard to achieve when the calculation size is increased and the grid number is bigger. Numerical simulation for high Ra turbulent convection faces some major challenges. So the direct (non iterative) solution method of efficient large-scale parallel computation for the 3D turbulent convection is created in this paper. Main difficulties are the parallel computing technology for the pressure Poisson equation. The mass efficient parallel approximate solution with the block tridiagonal equations of OpenMP and MPI used simultaneously after decoupling pressure Poisson equation using FFT is presented. Through the validation of the efficiency of this method in parallel computing, the new method for direct solution of parallel computing have good parallel efficiency and computational time. Results of thermal convection in 3D narrow cavity show that the convection characteristics calculated by using the new method is reasonable. The direct solution method for efficient large-scale parallel computation of 3D turbulent convection created in this paper also is likely to be a breakthrough in computing technology about efficient large-scale parallel computing incompressible NS equations in some special cases.