Abstract: Diagnostic techniques for temperature rise in the plate with the thermoelement and the thermal image visualiser,Reflectivity measured by the integrating sphere-optoelectron conversion amplitication,mass and molten mass measured by the metallographic microscope photographs and the electronic balance under laser irradiated are presented.The experimental measurements of the effective thermal coupling coefficients α_eff and thermal coupling α_a of LF6M aluminum alloy plates irradiated by the CW/COIL（wavelenth 1.315μm）has been performed.when laser intensity I ranges from about 0.60kW/cm² to 1.13kW/cm² and plate’s melt occurs,α_eff is between 0.16 and 0.18 and α_a≈0.20～0.25（as-received ）;α_eff 0.11 and α_a≈0.12～0.14（roughness 1.6μm for polished）,For I≈ 0.07～0.11 kW/cm² nad not melted. α_a≈0.09～0.10（as-received）,and α_a≈0.02～0.03（roughness 1.6μm for polished）