A new burner with a multi-flame structure is proposed for high-rate fabrication of optical fiber preforms in the vapor-phase axial deposition process (VAD). In this multi-flame VAD process, the synthesis of fine glass particles was clarified and the fabrication of soot preforms was investigated together with the consolidation process. As a result, a deposition rate of 4.5g/min was achieved using one double-flame burner. Graded-index core preform size was increased to 2500g. In addition, fibers with a high numerical aperture (N.A.) of 0.28 were fabricated using a double-flame burner. A transmission loss at 1.62µm was 0.54dB/km and the bandwidth at 1.3µm was 440 MHz km.