We report an in-depth investigation on the out-of-plane lower critical field Hc1 of the KCa2(Fe1～xCox)4As4F2(12442-type,x = 0,0.1).The multi-gap feature is revealed by the kink in the temperature-dependent Hc1(T)curve for the two samples with different doping levels.Based on a simplified two-gap model,the magnitudes of the two gaps are determined to be △1=1.2meV and △2=5.0 meV for the sample with x=0,△1=0.86 meV and △2 = 2.8 meV for that with x = 0.1.With the cobalt doping,the ratio of energy gap to critical transition temperature(△/kBTc)remains almost unchanged for the smaller gap and is suppressed by 20％ for the larger gap.For the undoped KCa2Fe4As4F2,the obtained gap sizes are generally consistent with the results of angle-resolved photoemission spectroscopy experiments.