The Laser Metal Deposition (LMD) as a process of additive manufacturing provides a highly accurate deposition of different materials at various locations and yields ideal adaptation for the fabrication of functionally graded materials. The fact that LMD lacks reproducibility makes it difficult and costly for related research solely carried out by experiments. Furthermore, the slow speed for fabrication also inhibits scientific works on this subject. The Simulation of LMD Process by means of mesh-free method like incompressible Smoothed Particle Hydrodynamics (ISPH) serves an effective way to find out the relationship between structure, process and properties of LMD. It also provides a way for virtual design to improve the accuracy and efficiency of LMD process. Two sub-processes are included in this project: one is the simulation of powders falling along nozzles which is modeled by discrete-element-method (DEM). The other process that is also the main part of LMD is to simulate the molten powders depositing on the substrate by using ISPH. For the purpose of improving efficiency, the DEM process and SPH process are coupled by means of techniques of intercommunication. The fundamental physical concepts involved in the LMD process are surface tension, Wetting effect, recoil pressure, heat radiation, conduction and convection. Each of those needs to be modeled and integrated into the final simulation. In this work, the correctness of kernel function and its gradient is employed in order to rectify the errors caused by the truncation of the support from the kernel function. With this correctness, the multiple physical models become more compatible and yield a stable and reasonable result.