A man has been sent to prison after a six-week old baby was found with eighteen historical fractures.

Benjamin Lin was sentenced to six years and nine months imprisonment at the Wellington District Court today after pleading guilty to two charges of wounding with intent to cause grievous bodily harm.

The charges included the 25-year-old shaking and squeezing the baby over the first weeks of the child's life.

The infant was later found in hospital with multiple fractures, including to his neck and ribs.

In court, Judge Denys Barry said Lim had effectively denied the child treatment.

He said he was the only one who knew he had been torturing this child for weeks.

Judge Barry said it was good recovery was on the cards for the baby but the full effect wouldn't be known for years.