If u had a hernia surgery 3 years ago is it normal to hurt sometimes ?

Probably ok: Occasional mild pain at the site of a previous hernia repair is relatively common. If the pain is new or severe, it should be re-evaluated for recurrence.

Likely normal: I am assuming you had a groin hernia fixed. Mild intermittent pain can be normal after this type of surgery, even many years later. It may fall into a category of pain known as inguinodynia, which can be difficult to treat. If the pain is debilitating, it may worth seeking surgical intervention. Otherwise it is usually treated with NSAIDs/rest/ice packs and sometimes by cortisone injection.