Combustor parameter of all gas-phase iodine laser is studied using the power of HF fundamental laser as a test criterion. The experimental results show that optimal F flow rate can be obtained as the excessive NF3 flow rate of 30%～70% is used for D2 flow rate of 10～20 mmol/s. Addition of attenuant He is a disadvantage for the F atom production. F atoms can be replaced by Cl atoms with enough DCl added. A source of Cl atoms is prepared for the study of all gas-phase iodine laser.