The　low　signal-to-noise　ratio　is　a　major　challenge　for　ultrasonic　inspection　of　coarse　crystal　structures,　which　is　caused　by　the　large　amount　of　scattering　noise　generated　by　coarse　grains.　To　overcome　the　insufficient　of　the　traditional　signal　denoising　method　in　waveform　distortion　and　amplitude　attenuation,　an　overlapping　group　sparse　variational　method　based　on　the　non-convex　penalty　function　is　proposed　for　ultrasonic　signals　denoising.　Based　on　the　typical　ultrasonic　signal　containing　scattered　noise,　the　influence　of　the　main　parameters　of　the　sparse　variational　method　for　overlapping　groups　of　nonconvex　variables　(such　as　the　type　of　function　of　nonconvex　variables,　regularization　parameters　and　multiplication　factors)　on　its　noise　suppression　effectiveness　is　analyzed,　and　the　basis　for　determination　of　suitable　parameters　in　processing　of　ultrasonic　signals　is　determined.　On　this　basis,　the　overlapping　group　sparse　variational　method　is　applied　to　the　noise　suppression　of　ultrasonic　signals　detected　from　steel　ingot.　Results　show　that　the　method　can　effectively　suppress　the　scattering　noise　in　ultrasonic　signals　detected　from　steel　ingot　and　improve　the　signal-to-noise　ratio　of　ultrasonic　imaging　by　more　than　6　dB.　The　research　work　is　a　useful　exploration　for　ultrasonic　detection　of　coarse　crystalline　materials.　©　2022,　Science　Press.　All　right　reserved.