Aimed at the problem that the Underlay mode power control algorithm based on energy efficiency fails to accurately reflect the interference performance between the secondary users and the primary users resulting in system capacity degradation, the interference efficiency is defined as the ratio of the total transmission rate of the cognitive satellite user to the interference received by the terrestrial base station, taking into consideration of the limited energy of the secondary users and the difference between the satellite link and the terrestrial link, an interference efficiencybased uplink power allocation model for satelliteground cognitive networks is established. On the basis of the abovementioned, an interference efficiencybased power allocation algorithm is proposed. By introducing the interference threshold constraint and the signaltonoise ratio constraint, the optimal power is solved by using the nonlinear fractional programming theory and the Lagrange duality method. The simulation results show that the algorithm in this paper can effectively reduce the interference to the primary user and improve the interference efficiency of the system under conditions of premise in satisfaction of the communication quality of secondary user.