In view of the disadvantages of small allowable gap and large thermal damage in non-optical contact glass welding, a 50 W infrared picosecond laser, equipped with a 100 mm long focal scanning galvanometer, was employed to investigate the influence of laser scanning number on the welding morphologies in this study. The silica glass welding joint with low heat damage zone was obtained via non-optical contact by quasi-simultaneous welding method, and the allowable gap of welded joint was increased to 5 μm. The experimental results demonstrate that the cavities produced by the glass gap exist in the form of bubbles in the molten pool. With the increase of scanning times, the cavities are far away from the original glass interface and the upper and lower glasses are fused to form a strong bonding force. The maximum welding strength was improved to 21.42 MPa under the process parameters with single pulse energy of 24 μJ，scanning speed of 1 000 mm/s, defocusing amount of -100 μm and scanning number of 5 times; meanwhile, it still can reach to 15.79 MPa under such large welding gap of 5 μm.