The　traditional　cropping　processes　have　some　disadvantages,　such　as　poor　surface　quality,　low　yield,　the　waste　of　materials,　and　high　energy　consumption.　The　low　cycle　fatigue　precision　cropping　process　with　circumferential　loading,　which　is　a　new　type　of　precision　cropping　process,　is　studied.　According　to　the　stress　concentration　effect　of　the　V-shape　notch,　the　fatigue　crack　on　the　tip　of　the　V-shape　notch　is　prompted　to　initiate　and　extend.　The　working　principle　of　the　precision　cropping　machine　is　described.　The　criterion　that　whether　the　crack　on　the　root　of　the　V-shape　notch　is　initiated　or　not　is　provided　under　the　effect　of　low　cycle　fatigue　loading.　The　materials　which　are　0.2%C　steel,　H59　copper,　0.45%C　steel,　20Cr　steel,　and　LY12　aluminum　are　tested　under　two　control　curves.　The　initiation　and　propagation　of　crack　are　accelerated　and　the　good　cross　sections　of　the　metal　bar　are　obtained.　The　results　show　that　the　mean　stress　of　the　metal　bar　in　the　cropping　process　can　be　effectively　reduced　due　to　the　stress　concentration　effect　of　the　V-shape　notch.　The　metal　bar＇s　stable　crack　propagation　and　fracture　can　be　obtained　when　constantly　increasing　striking　displacement　and　reducing　the　striking　frequency　in　the　cropping　process　at　the　same　time　in　the　process.