Abstract: With the development of ion confinement technology and laser cooling technology,the quantum frequency standard is developed from microwave band to optical band,and the uncertainty of ion optical frequency is raised to E-19 magnitude.The ion confinement system is one of the core systems for realizing ion optical frequency standard,which mainly applies the Paul trap to confine ions by the radio frequency field and electrostatic field.We introduce the principle of Paul trap and the equations of ion’s motion.Recent progresses on the ion trap structure in optical frequency standard have been presented,including ring-cap traps,end-cap traps,miniature segmented traps and blades traps.The development of ion traps can help promoting the stability and miniaturization of optical frequency standard.

Key words: Paul trap, Ion motion, Optical frequency standard