A study of heat transfer and thermophoretic particle deposition has been carried out for the Modified Chemical Vapor Deposition(MCVD) process. A new concept utilizing two torches is suggested to simulate the heating effects from repeated traversing torches. Calculation results for the wall temperatures and deposition efficiency are in good agreement with experimental data. The effects of variable properties are included and heat flux boundary condition is used to simulate the moving torch heating. A conjugate heat transfer which includes heat conduction through solid layer and heat teansfer in a gas in a tube is analyzed. Of particular interests are the effects of torch speeds and solid layer thicknesses on the deposition efficiency, rate and the tapered entry length.