In order to study the damage evaluation of specimens mainly subject to bending in steel structure buildings, a three-point bending test was conducted on the Q235 steel plate specimen to collect the magnetic memory signal value Hp(y) during the loading stage of the specimen, multiple magnetic memory signal characteristics are introduced to characterize the damage of steel structures. The experimental results show that the stress concentration area can be determined by the phenomenon of “ peak” and “ trough “ of the magnetic memory curve and the phenomenon of“peak-peak” of the magnetic memory gradient curve. It can be found that the tensile of the specimen is sensitive to the yield of the specimen through other relevant characteristic quantities ΔHp curve, Sh and | K | max curve. The “inflection point” of the ΔHp -F curve and the “ peak” of the | K | max -F curve are used as the basis for the specimen to enter the yield. The study is applicable to the prediction of structural damage characterization, and the feasibility of magnetic memory detection in steel structure damage is verified by multiple parameters.