The man, who has not yet been formally identified but is believed to be local and in his 40s, was found at an address in Croft Bank on Wednesday evening.
He had been the victim of stab injuries and was pronounced dead in hospital a short time later.
A local man aged 25 and a local woman aged 36 have been arrested in connection with the death and are in custody being questioned.
DI Helen Evans, from East Midlands Special Operations Unit (Major Crime) said: “We are investigating the circumstances that led to this man’s death.
“We believe he attended a funeral wake earlier that afternoon in Wainfleet and would like to trace anyone who was in the Woolpack Pub and who may have witnessed an altercation at the location.”
Anyone with information should contact Lincolnshire Police by dialling 101 and quoting incident number 348 of 2 March. Report crimes anonymously by contacting Crimestoppers on 0800 555 111.