According　to　the　concept　of　critical　plane,　a　fatigue　life　prediction　method　is　presented　under　random　multiaxial　loading.　Firstly,　a　multiaxial　cycle　counting　method　is　proposed　based　on　the　von　Mises　equivalent　strain　and　equivalent　stress　concept,　sign　correctional　formula　and　traditional　uniaxial　rainflow　cycle　counting　method.　This　method　mainly　aimed　at　solving　the　problem　of　＇sign　lost＇　in　von　Mises　equivalent　strain　and　equivalent　stress　history　under　multiaxial　random　loading,　suggesting　adopt　a　sign　formula　correct　it,　then　cycle　count　the　von　Mises　equivalent　strain　history　with　a　traditional　uniaxial　cycle　counting　method,　which　can　not　only　be　convenient　for　evaluating　the　damage　of　succeeding　procedure,　but　make　the　uniaxial　cycle　counting　method　successfully　apply　in　multiaxial　load-time　history.　After　that,　the　normal　and　shear　strains　are　analyzed　for　cycle-counted　equivalent　strain　cycles,　and　the　critical　plane　as　well　as　fatigue　damage　parameters　are　also　defined　for　these　cycles.　Finally,　combining　several　familiar　multiaxial　fatigue　damage　models,　Miner＇s　linear　rule　together　with　uniaxial　fatigue　data　of　En15R　steel,　predicting　its　fatigue　life　under　random　axial-torsional　loading,　and　the　results　show　that　the　life　predictions　agree　well　with　experimental　results.