Indium tin oxide (ITO) films have been widely used in optoelectronic devices, such as solar cells, organic light emitting diodes, liquid crystal devices and so on. The simple and efficient laser annealing technologies have been employed to achieve the desired structure and properties of the films for practical applications. We focus on an 1064nm quasi-CW laser annealing, which is maybe an alternative low-cost choice compared with the current excimer and fs laser annealing. Effects of 1064nm quasi-CW laser annealing on the optical performance, electrical property and chemical composition of the ITO film were investigated in detail in this paper. It was found that the ITO film surface appeared discoloration annealed by 2000 W/cm2. Experimental results showed the transmittance of the above annealed ITO film at near-infrared band was improved obviously and the electrical sheet resistance was increased slightly compared with that of the unannealed film. The improvement of the transmission at 1064nm of the annealed film come from the reduction of absorption. The XPS analysis results showed a modification of rations of oxygen and Sn2+ after laser annealing, indicating the reduction of oxygen vacancy and free electrons, were responsible for the optoelectrical property modification of ITO films. However, when the higher annealed laser power density was utilized, the ITO film surface occurred laser-induced cracks. The annealing mechanism was discussed.