Sensory cortex neurons of non-classical receptive field on the classical receptive field adjustment widely exist in mammals, is considered to be the basic characteristic of the sensory cortex neurons. In primary visual cortex of mammals, there was a larger non-classical receptive filed (nCRF) region beyond the classical receptive field (CRF). Although the region was not directly respond to the visual stimulus, it can modulate cell’s response in classical receptive fields. Understanding the modulatory mechanism of non-classical receptive field in V1 neurons can reveal the basic principles of information processing in mammalian sensory cortical neurons. At present, many studies found that modulatory mechanism of nCRF arises from feed forward, horizontal, and feedback interactions with local recurrent connections through synaptic mechanisms involved in increased inhibition and reduction of recurrent excitability. The modulatory by nCRF can effectively reduce the redundancy of the visual input. In general, surround suppression is generated by multiple connection types. Feedforward and horizontal connections in V1 mainly provide surround suppression from just outside the classical receptive field, and feedback from progressively higher areas provide modulation from progressively more distant surround regions. Moreover, feedback connections from different cortical areas likely modulate V1 responses in a stimulus-specific fashion, which is crucial for the large-scale information processing in the primary visual cortex.