I had a left inguinal hernia surgery in 2010 from a year whenever i ejaculate i feel pain in my surgical area for 3 days after that pain gone. reason?

Cannot tell you: For sure unless I have more details and exam. Ask the surgeon who did your hernia repair for re-exam to see if he can determine whether your pain is related to the surgery.

Musculoskeletal: The muscle and fascia in the groin are caught up in scar tissue and the physical trauma or use of muscles in the area get inflamed and hurt. Does it hurt after masturbation? If so, then it is complicated but if it only occurs with intercourse then you may benefit from steroid injections in those scarred areas. Most surgeons don't deal with this and refer patients to pain specialists.

Maybe mesh related?: It's hard to exactly why your symptoms are occurring without knowing more about the type of repair and how soon after your surgery the pain began. It sounds like there may be irritation of the vas deferens (tube that carries semen from testicle to urethra). Possibly related to mesh used for repair of your hernia.