Emergency services were called to the A16 between Sibsey and Stickney at 12.50pm yesterday after a red Ford Focus was involved in a collision with an HGV.
The driver of the Focus, believed to be a 74 year-old man from Boston, died at the scene.
A 52 year-old man who was driving the lorry was arrested on suspicion of causing death by dangerous driving and remains at Spalding custody being interviewed.
Police are appealing for any witnesses to contact the Collision Witness Hotline on 1522 558855.
The road was eventually reopened at 10pm.