A low-diffusion preconditioning Roe scheme was proposed by using an adjustable parameter in preconditioning Roe scheme to control the numerical dissipation and the adjustable parameter value rules. The low-diffusion preconditioning Roe scheme reflected the real physical dissipation in the extremely low-speed zone. In the region similar to the inflow speed

low-diffusion preconditioning Roe scheme could ensure the stability of the flow field. The low Mach/low Reynolds number steady solutions of viscous flow passing a circular cylinder and the low Mach/high Reynolds number steady solutions of viscous flow passing NACA0012 were satisfied. Numerical results show the efficiency of the new scheme to simulate low Mach number flows.Numerical experiments show that the numerical dissipation of the scheme has a notable effect on low-speed flow numerical simulation with preconditioning method.