Low-temperature specific heat (SH) is measured for the 12442-type KCa2Fe4As4F2 single crystal under different magnetic fields.A clear SH jump with the height of ΔC/T|rc =130 mJ mol-1 K-2 is observed at the superconducting transition temperature Tc.It is found that the electronic SH coefficient Δγ(H) quickly increases when the field is in the low-field region below 3 T and then considerably slows down the increase with a further increase in the field,which indicates a rather strong anisotropy or multi-gap feature with a small minimum in the superconducting gap(s).The temperature-dependent SH data indicate the presence of the T2 term,which supplies further information and supports the picture with a line-nodal gap structure.Moreover,the onset point of the SH transition remains almost unchanged under the field as high as 9 T,which is similar to that observed in cuprates,and places this system in the middle between the BCS limit and the Bose-Einstein condensation.