N doped Ti0 2 films were deposited by direct current pulse magnetron sputtering system at room temperature. The influence of 0 2 flow rate on the crystal structure of deposited films was studied by Stylus profilometer, X-ray photoelectron spectroscopy, and X-ray diffractometer. The results indicate that the 0 2 flow rate strongly controls the growth behavior and crystal structure of N doped Ti0 2 film. It is found that N element mainly exists as substitutional doped state and the chemical stiochiometry is near to TiO 1.68±0.06 N 0.11±0.01 for all film samples. N doped Ti0 2 film deposited with 2 sccm (standard-state cubic centimeter per minute) 0 2 flow rate is amorphous structure with high growth rate, which contains both anatase phase and rutile phase crystal nucleuses. In this case, the film displays the mix-phase of anatase and rutile after annealing treatment. While N doped Ti0 2 film deposited with 12 cm 3 /min 0 2 flow rate displays anatase phase before and after annealing treatment. And it should be noticed that no TiN phase appears for all samples before and after annealing treatment.