One of the best ways to enhance heat transfer coefficient is by improving thermal properties of the working fluid. Gold/water nanofluid flow through horizontal minitube with very low Reynolds number was simulated by using Thermal Lattice Boltzmann Method (TLBM) under uniform heat flux boundary condition. The effect of different volume fraction of nanoparticles on the heat transfer coefficient was studied and compared with the base fluid (water). The results were verified using Finite Volume Method (FVM). The results showed enhancement of heat transfer coefficient when using gold/water nanofluid and this enhancement depends on the volume concentration of Gold nanoparticles. The maximum enhancement was 18% with 0.03 volume concentration.