To　enhance　the　anti-jamming　capability　of　cyberspace　data-link　(CDL)　in　the　complex　electromagnetic　environment,　we　explore　the　problem　of　the　image　interference　caused　by　IQ　channel　imbalance　in　simultaneous　transmit　and　receive　based　cognitive　anti-jamming　(SCAJ)　system.　The　interference　sensing　of　single-and　multi-channel　SCAJ　system　impaired　by　IQ　channel　imbalance　is　investigated,　and　energy　detection　based　detection　and　false　alarm　probabilities　in　closed-form　for　SCAJ　system　are　derived.　Simulation　results　show　that　the　detection　probability　of　the　SCAJ　receiver　is　decreased　by　IQ　channel　imbalance,　and　the　proposed　interference　cancellation　scheme　can　reduce　the　adverse　effect　of　IQ　imbalance.　©　2017,　Editorial　Board　of　JBUAA.　All　right　reserved.