Dysfunction in social interactions is a core symptom of autism spectrum disorder (ASD). Nevertheless, the neural mechanisms underlying social deficits in ASD are poorly understood. By integrating electrophysiological, in vivo fiber photometry, viral-mediated tracing, optogenetic and pharmacological stimulation, we show reduced intrinsic excitability and hypoactivity of SOM interneurons in medial prefrontal cortex (mPFC) in Magel2-deficient mice, an established ASD model, were required to social defects. Chemogenetic inhibition of mPFC SOM-containing interneurons resulted in reduced social interaction in wild-type Magel2 mice. These sociability deficits can be rescued by optogenetic activation by excitability of SOM in the mPFC and mPFC