We used Doppler-free intermodulated fluorescence technique to study the hyperfine sturcture of some levels of La I in a home made La-Kr cathode discharge. The A and B constants for the levels 20197.34cm, 21447.86cm are reported for the first time. We observed a homogenous linewidth of less than 40MHz and all crossover lines between transitions with common lower levels. The spectral characteristics of a cathode discharge are investigated.