By basing on the study and manufacture of the technical integration experiment line (TIL) prototype laser facility, and using the method that theoretical simulations guide experiments and experiment results check programs, the actors affecting third harmonic generation (THG) efficiency for large-aperture, high-intensity inertial confinement fusion (ICF) laser facility have been analyzed and studied in detail. Furthermore, the output-ability of THG system for ICF driver has been discussed adequately. As shown through experiment results, when average drive irradiance of fundamental light, I1ω is 2.7 GW/ cm2, measured value of THG efficiency is 50%～55% and the theory value is 60%, which indicates that the experiment result can be agreed with the theory value well. The experiment results will provide experiment proofs and calculation tools for eight beam eligibility and power balance of prototype laser facility.