Abstract: To meet the demand for long-life carbon nanotube field emission cathode in deep space exploration, the failure mechanism of CNTs cathode was investigated, and a long-life CNTs cathode design was introduced. Patterning the CNTs as an array of CNTs island offers a way to eliminate the shielding effects of electrical field. In this way the areas of emitting CNTs are larger, which avoids over-heating on a small emission area. A bonding technique was introduced, the contact between CNTs and substrate was maintained by molecular forces previously, melting metal was introduced as the bonding layer. The mechanical robustness of the CNTs cathode was enhanced while the electrical/thermal resistance was reduced. Performance tests were conducted on the prototype in a high vacuum environment. The prototype produced a current of 0–1 mA with a resolution less than 2 μA and the noise level was less than 1 μA/Hz^1/2@0.01–1 Hz. The prototype was tested by over 550 hours' continuous emitting, showing good stability in long-term use.