Abstract: In order to investigate the influences on ablation quality of quartz glass by the linearly and circularly polarized femtosecond lasers, the line ablation experiments of different scanning velocity and the surface ablation experiments of different line overlap rate were conducted. The influences of linearly and circularly polarized lasers on ablation line width were researched. In addition, the ablation line and surface morphology were observed using ESEM and optical microscope, respectively. Besides, the surface roughness was analyzed using the 3D surface profiler. The results show that the line width of linearly polarized laser is greater than that of circularly polarized laser, and the greater the laser power, the line width difference becomes more remarkable. Whats more, when the line overlap rate is in the range of 65%-90%, the surface roughness of linearly polarized laser increases with the increasing of overlap rate, and it reaches 1.33 m when the overlap is 65%. But the arithmetical mean deviation of line contour decreases firstly and then increases with the increasing of overlap rate, and it reaches to a minimum of 1.05 m when overlap rate is 80%. When the overlap rate is not more than 80%, the arithmetical mean deviation of line ablation surface by the linearly polarized laser is lower than that of circularly polarized laser, and when the overlap rate is 90%, it is higher than that of circularly polarized laser.