Molecular dynamics simulations based on the Brenner potential, a tight-binding method, and the Car-Parrinello algorithm were performed to explore the conditions for pulling out long monatomic chains from a graphite layer. The results show that the method of pulling, the ambient temperature, and the pulling speed are important factors. The simulations indicate that free monatomic carbon chains with macro length can be obtained at about $1000\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ if the pulling speed is much lower than $30\phantom{\rule{0.3em}{0ex}}\mathrm{m}∕\mathrm{s}$.