Nowadays numerical methods are as complement of experimretal works for nano-scale studies. Molecular dynamics simulation (MDS) is more determined method for molecular simulation. We employ MDS for Poiseuille flow simulation in nano-channel. In this thesis, main porpuse is about implicit wall models instead of explicit wall models. Various implicit or stochastic wall models sach as spcular and diffuse Maxwell, Maxwel-Type, CL and CLL, Maxwell-Yammamuto, thermal wall and Nokilla, investigated and use them for simulation of Poisseul flow in nanochannel. These wall models can be calculated velocity components of reflective molecules that collide with implicit wall. With this method we can omit molecules of wall and predict the outcoming of it’s velocity after collide with wall. Most advantage of these models is that they can reduce time of simulation. Accommodation coefficient (AC) is a factor for determination of properties change via collides with wall. In the recent years, open source softwares widely use for various scientific subjects such as molecular science and molecular simulation. LAMMPS (Atomic Molecular Massively Parallel Simulator Large-scale) is one of the more applicable and famous of them. In the 5 recent years, many of researchers use it for their subjects and develope it for various subject of molecular science simulation. We use it for our subject. Scripts of Implicit wall models and calculation of accommodation coefficients are not in it and we should add their scripts (with C++ Programming accordance to MPI library and Objects Oriented Programming) to the LAMMPS. In the first chapter, present basics of MD method and its algorithms, in chapter two, an introduction to various implicit wall models and accommodation coefficient is given and details of them studied. In chapter three, explain the simulation details that used in this thesis. In the chapter four, first, verified Script of Poiseuille flow with 3D simulation of liquid argon confined in Pt walls and then simulate 2D poiseuille of gas and liquid argon with explicit model and implicit wall models by employing various conditions (forces, density number and temperature), Then present the results of these simulations. These results consist of velocity and shear stress profile across channel and accommodation coefficient of them and compare the results of all wall models together. Then conclude that CLL and Maxwell-Yammamotu wall models are the best model for our simulation. In the end, there is a summary of thesis and suggestions for further studies. This thesis consists of an addendum for more explain about Maxwell distribution and related equations. We can concluded, the implicit wall models can be predicting the properties of fluids (Gas and Liquid of Argon) in nano-channel. The results deduced that specular wall model has good agreement with simulation of smooth-wall explicit wall. It should be reviewed that implicit wall models (except specular and nokilla models) needed ACs for each model. These ACs calculated from explicit wall simulation and then used them in implicit models. Keywords: Explicit wall and implicit wall models, Accommodation coefficient, Nanochannel, Poiseuille flow and molecular dynamic