In view of the lack of reliable testing methods for the effective tension of end anchor of external prestressed strand，the mechanical mechanism of testing the tension of end anchor by the reverse tension method was revealed based on the mechanical mechanism of mechanical equilibrium and deformation coordination． And the theoretical testing error under the most unfavorable conditions was analyzed，and the applicable conditions of the method were pointed out. Finally，based on the most commonly used construction machines and equipment in the construction site，a practical test method and system composition were put forward and verified on the indoor static load anchorage test machine． The test results show that the sensitivity of different parameter curves in judging tension force under strand anchor is:  forcedisplacement  curve ＞ force-time curve ＞ displacement-time curve． The test accuracy of the proposed method can meet the requirements of engineering accuracy．