The invention belongs to the field of power transmission and transformation line construction, and particularly relates to a dynamic impact true model test method for a crossing net in tension stringing and a device implementing the method. An impact cable is installed on an iron tower, one end of the impact cable is anchored on the ground, and the other end of the impact cable is wound on a traction machine; the suspension cable crossing net is built below the impact cable, and a ruler, a camera, a sensor signal receiving station and a theodolite are erected in the center of the suspension cable crossing net to form the dynamic impact true model test device; and the test device adopts a pull-off type releaser, when pulling force of the impact cable reaches set traction force, the pull-offtype releaser is pulled off, the impact cable falls to impact the crossing net, and impact test data are recorded through the ruler, the high-speed camera, the sensor signal receiving station and thetheodolite. According to the test method and device, the safety of tension stringing crossing construction can be improved and safe and stable operation of a crossed power line is ensured.