The modified chemical vapor deposition (MCVD) process is one of the most widely used processes to manufacture the optical fiber preforms. In this process, O2, SiCl4 and dopant (GeCl4, POCl3 or BCl3) are fed into the rotating silica tube which is externally heated by a axially traversing oxy-hydrogen torch. In the reactor, oxidation reactions occur and result in fine oxide particles which deposit on the tube wall due to thermophoresis; that is, from the net force that a suspended particle experiences in the direction of decreasing temperature. This deposition process mainly depends on the thermophoretic deposition of the particles on the substrate tube. A modification of this MCVD process is considered with an axial heating of laser beam in order to improve the deposition efficiency of this process. CFD simulations of the MCVD process with and without laser heating are carried out. The different powers of lasers are used to investigate the effect of laser heating on different parameters. The detailed analysis of the MCVD process are presented and finally a comparative study is conducted to examine the effect of laser heating on different parameters such as thermophoresis, conversion rate and deposition efficiency. Axial heating in the MCVD process results in high thermophoresis and subsequently high deposition efficiency.