John McCallum,53, abused Rachel Steadwood and Tracy Brown at various times from 1978 to 1987 at different locations in Scotland.
The High Court in Edinburgh heard that the girls were aged five when McCallum began abusing them.
Earlier this month, a trial heard that the sisters - who have waived their right to anonymity - kept quiet for years about a catalogue of abuse inflicted on him.
In the trial, the court heard how the offences came to light 15 years ago when one of his victims had flashbacks of what happened to her as a child.
He was convicted and sentence had been deferred in order for the court to obtain character reports.
Yesterday, the High Court heard how McCallum, who was represented by one of Scotland's top defence lawyers, still denies his guilt. He claimed Frances McMenamin QC and her assistants did not do their jobs properly. He also thought female jurors had been prejudiced against him.
Judge Lord Boyd told McCallum: "You were very ably represented by senior and junior counsel. The offences for which you have been convicted of are grave ones and must be marked by a substantial period of imprisonment. The sentence will be one of 10 years."
The two women gave evidence against McCallum of Loanhead, Midlothian, during a week long trial.
They told the jury how the father of two molested them during visits to a travellers' site in Edinburgh and at a house in Loanhead, Midlothian, and elsewhere.