Abstract: In this paper, the molecular model of diamond was established based on the Tersoff potential function and molecular dynamics (MD) method. Through analyzing the atomic bonding structure, radial distribution function (RDF) curves, and the atoms’ coordination number during different melting temperatures and cooling processes, the formation mechanism of atomic morphology hybridization during the preparation of diamond like carbon (DLC) films was revealed at the atomic scale. The results show that the DLC film is mainly composed of C-sp³ and C-sp² hybrid phases. When the temperature is lower than 6000 K, the melting and cooling process will not cause the structural transformation of the C-sp³ hybrid, and the properties of the films are relatively stable. When the temperature is higher than 7000 K, a large number of C-sp³ hybrid atoms are transformed to C-sp² and C-sp¹ during melting. In the cooling and relaxation equilibrium process, the high energy state C-sp³ hybrid atoms will be transformed to C-sp², but the number of C-sp¹ hybrid has little change. The melting temperature has a major effect on the percentage content of C-sp³ and C-sp² phases during the preparation of DLC films. When the content of C-sp² hybridization exceeds 40% in the system, the properties of the films tend to be graphitic.