We probe into the dynamics of interacting non-Markovian information systems. The stochastic dynamics of information has two aspects: the self-evolution and interaction. We show that self-evolution of a non-Markovian information system can be described by a Markov-type master equation with memory dependence. We also reveal that the interaction between systems can be fully embodied into the information dynamics of the composite information system. To characterize time-irreversibility of the self-evolution and the interaction, we apply the landscape-flux theory to both stochastic and thermal information dynamics.The driving force of the nonequilibrium information dynamics can be decomposed into time-reversible (detailed balance preserving landscape part) and -irreversible (detailed balance breaking nonequilibrium flux part) parts. The time-irreversible part of the driving force fully depicts the time-irreversibility behavior in the stochastic dynamics. The time-irreversibility of the interactions between systems reflected in nonequilibrium thermodynamics can be seen in the decomposition of the mutual information rate which corresponds to decomposition of the driving force. In particularly, the time-irreversible part of mutual information rate reveals the underlying relationship among the entropy production rates of the information systems. We propose the finite memory approximation method and demonstrate that the above mentioned features can be found in a wide class of non-Markovian nonequilibrium information systems. Finally, we derive the lower and upper bounds for informational entities under concern with clearly meanings.Studies on the nonequilibrium behaviors of two interacting systems with finite states have shown their importance in meso-and microscopic information dynamics [1][2][3][4][5][6]. Usually, the dynamics of interacting systems in random environments with time-invariant parameters (temperatures, chemical potentials, etc.) and infinite degrees of freedom is always considered to be non-Markovian with finite memories [7]. Although the usual analytical and numerical methods for Markov processes can be also applied for getting the pictures of both stochastic dynamics and thermodynamics of a composite Markov system, it has been proven to be difficult that we can depict the behaviours of the subsystems with the same ingredient. This is because the two subsystems may also be random environments with time-variant parameters for each other due to the comparable sizes and state-switching rates of the subsystems. This indicates that none of the subsystems needs to be Markovian. Because of the existence of the interactions, every subsystem has to adjust itself to adapt to the time-variant environment (the other subsystem) and then the corresponding process shows a remarkable path-dependence by summing away the degree of freedom of the other subsystem, which means it has a memory. The Information of the past states in a memory are always embedded into the parameters of the dynamics of the system to determine the ...