Time-of-flight mass spectroscopy and quartz crystal oscillator are used to analyze the evaporation properties of the reservoir oxide cathode coated nano-particle carbonates in decomposing and activating process at different temperatures. The results show that the purity of the reservoir oxide cathode is high. It can fully be decomposed and activated in the conventional technologic process with more freed Ba and lower evaporation rate, compared with the conventional reservoir oxide cathode.