In order to design a third order lattice Boltzmann force model capable of recovering the Navier-Stokes equations applied to low viscosity flow

the force model proposed by Shan，et al were amended. The fluid velocity and total energy affected by force were redefined directly without any physical assumption. The Navier-Stokes equations （including the energy equation） were derived from lattice Bhatnagar-Gross-Krook(LBGK) equation via the Chapman-Enskog expansion without any error terms.