With density functional theory(DFT) and elastic scattering Green's function method,electronic transport of alkanemonothiol molecular membranes were simulated theoretically.It shows that conductive ability of molecular membranes increased 2 to 3 orders of magnitude than that of a single molecule due to interaction between molecules.Conductive ability of a molecular junction increases with increasing external force.Increase of current is mainly due to increased probability of tunneling within and between chains in a molecular junction.The increased probability is caused by coupling enhancement between molecule and electrode and between molecules.