[en] We propose a novel of THz radiation generation by beating two color lasers two color laser having fundamental frequency w and its frequency shifted second harmonic w2 in an carbon nanotubes (CNTs) array mounted on a metal surface. A nonlinear ponderomotive force is experienced by the free electrons of the nanotubes at frequency 2 w1 and w2 – w1 produces density perturbations. These density perturbations couple with the oscillatory velocity to give rise to nonlinear current density at beat frequency w2 – 2w1. Each nanotube mounted on the metal surface acts as an oscillating dipole antenna emitting terahertz radiation. The maximum terahertz power is obtained in those directions where phase difference between fields due to successive nanotubes is integral multiple of 2p. A resonant enhancement in the terahertz power is observed when beat frequency equals wp /√2 , where wp is the electron plasma frequency of the nanotube. (author)