TMZ has obtained the complete transcripts of Mitt Romney's testimony -- which he's accused of lying under oath to screw over his friend's ex-wife.

The testimony was given in 1991 at Norfolk Probate and Family Court in Massachusetts.

During his examination, Romney was asked how he first became acquainted with Staples and Tom Stemberg. Romney explained ... a venture capital businessman from another firm "mentioned to me a gentleman named Tom Stemberg had a business plan to commence an office supply chain and was looking for capital to fund that."

Romney continued, "I told him I didn't think it was a very good idea, but I'd look at it."

2:45 PM PT -- If you enjoy learning how business people valuate stocks, you're gonna LOOOOVE these documents.