A ceramic-based pulse-forming line (PFL) is a solid-state device with a wide range of applications in compact pulsed power systems. In this paper, the characteristic impedance of a ceramic-based PFL is theoretically analyzed, and an improved PFL based on an impedance matching electrode is proposed. The improved PFL effectively increases the flat-top ratio and reduces the rise and fall times, enhancing its potential applicability. Experiments using the improved PFL show that, under a charging voltage of 33 kV and with an impedance matching load, the output pulse width can reach 86 ns with a matching impedance of 3.9 Ω. The improved PFL output waveform has a flat-top ratio that reaches 72%, compared with 49.5% in a typical PFL, and exhibits shorter rise and fall times.