The invention belongs to the technical field of network security, in particular to a Markov signal game-based moving target defense strategy selection method and device. The method comprises the stepsthat a signal game model and a Markov decision process are combined, a multi-stage Markov signal game model is constructed, the multi-stage Markov signal game model comprises a plurality of independent and similar single-stage signal game models, and the signal game of each single-stage signal game model belongs to a limited game; a target function is selected in the defense and confrontation process of the moving target, and a multi-stage game equilibrium solving result is obtained; and an optimal defense strategy is selected according to a multi-stage game equilibrium solving result. The dynamic confrontation process between the attacker and the defender is analyzed, multi-stage game equilibrium is solved, the optimal defense strategy is selected, the defects of passive defense in the field of network space security are overcome, the timeliness, objectivity and accuracy of system defense are improved, and the active defense capacity of network security is enhanced.