The simulation of Computational Fluid Dynamics (CFD) is helpful on the development process of thermal inkjet print head. Since the physical scale of bubbles is very small and the manufacturing process is money consuming, it takes engineers a lot of efforts and expenses to do the experiments. A very powerful CFD code as a quick analysis tool is necessary for designing an optimal product. This code must include two models, which are thermal bubble model and free surface tracking model, in order to simulate the printing process. Recently, A great improvement on the CFD code has been achieved.There are many parameters that influence the flying consistence and direction of the ink droplet. The viscosity and surface tension of ink are two important ones. This research focuses on the effect of the ink viscosity, surface tension and thermal conductivity to the flying behavior of the ink droplet. Four inks are used on this research and compared results with each other. A commercial CFD code is used to simulate the whole inkjet printing process. The 3D model and mesh are first created by a CAD tool and then inputted into the CFD commercial code. The processing time for the simulation is greatly shortened. A formula, which is a function of ink viscosity and surface tension, is generated by the results. The formula describes the relationship between the ink properties and droplet length. An experiment, which set up by research group, using a CCD camera to take pictures on every one microsecond is also preceded. This experimental equipment is a powerful tool for observation of inkjet print head. It includes CCD camera, control board, control program and computer. Comparisons between simulation and experiment results are shown in this paper. The conclusion will be helpful for the development of the inkjet print head.