This　paper　presents　the　design　and　implementation　of　a　true　random　number　generator　(TRNG)　for　smart　card　application.　Based　on　the　effect　of　the　oscillator　phase　noise　and　meta-stable　state　of　the　trigger,　the　random　number　is　generated.　An　efficient　calibration　method　can　correct　the　uniformity　of　random　number　sequences　and　improve　the　distribution　of　the　random　number.　The　prototype　of　the　TRNG　is　fabricated　in　a　0.18　mu　m　CMOS　technology.　Under　the　standard　diehard　test,　the　results　show　that　bit　rate　is　1Mb/s　and　the　TRNG　has　a　good　pass　rate　under　a　bad　condition.　The　power　consumption　of　the　TRNG　is　0.066mW　with　a　1.8V　power　supply.