The principle of coherent population trapping（CPT） atomic clock is presented and the methods for fabricating cavity with alkali metal for CPT atomic clock system is described.On the basis of comparison of these methods

a special machine for the atomic clock cavity with alkali metal fabrication is realized.Some cavities with rubidium are made.Test results show that it has good bonding quality

Rb element packaged in the cavity is pure

and it could be used for atomic clocks system.