Abstract: ‍ ‍Intelligent reflecting surface aided wireless communication technology is one of the frontier hotspots in B5G/6G research， which can intelligently shape the electromagnetic wave propagation environment to meet the high spectrum and energy efficiency requirements. IRS is mainly capable of a large number of passive array antennas， which enables real-time programmable control of directional reflection and beamforming of radio frequency signals. When an IRS is placed in a wireless communication system， a properly designed IRS can increase the received signal power of the intended user by optimizing the phase shift parameters， but it has potential interference enhancement to non-serving users and non-serving systems. This kind of interference is induced by cross-system IRS， which is similar to the conventional crosstalk mechanism， and is aptly called crosstalk interference. This paper investigated the crosstalk interference between multiple IRS systems operating in different frequency bands， including the spatial distribution of power radiation of the crosstalk signal and the technical factors that determine the crosstalk intensity. Firstly， based on the mathematical model of IRS cascade channel and the optimal phase design method of reflecting elements in a certain system， the beamforming gain matrix of the crosstalk was analyzed， and the computational expression of the channel model was given. Then， the quantitative relationship between the signal to interference ratio and azimuth and elevation angles of IRS reflecting signal was deduced， and the spatial distribution of crosstalk was analyzed from three aspects： carrier frequency， azimuth and elevation angle， and the number of the number of intelligent reflecting surface elements. Finally， the actual situation of crosstalk interference distribution was observed through numerical simulation. Numerical simulation results show that the crosstalk between IRS aided communication systems should not be ignored unless the user is in a specific location. The beamforming gain of crosstalk interference is related to the carrier frequency ratio between systems. Specifically， when the carrier frequency ratio is less than or equal to 1， the crosstalk interference can be effectively suppressed by increasing the number of intelligent reflecting surface elements； when the carrier frequency ratio is greater than 1， the crosstalk interference is further dispersed as the carrier frequency ratio increases.