Two different carbon nanotube (CNT) cathodes have been made by using screen-printing and also by coating. Pulse emission properties of the two cathodes were studied, and the cathode's surface morphology was characterized. Research results show that the CNT cathode is capable of generating pulsed beams of a few kilo-amperes. The pulsed field emission properties of the cathode were tested in a diode structure powered by a high-voltage generator(under conditions of 2×10-3 Pa, 100ns, 1.64MV). The results reveal that the emission current of the cathode made by coating can attain 5.11 kA, and the highest emission current density is 260 A/cm2. The stability of cathode made by screen-printing is better than that made by coating. The pulsed emission mechanism of carbon nanotubes is shown to be explosive electron emission. This carbon nanotube cathode appears to be suitable for high-power microwave device applications.