He was 73.
Mr Rangarao, a bachelor, died of a heart related ailment.
According to sources in his family, he went to a hospital on Wednesday evening and had come back after a check-up, but complications occurred and he passed away early in the morning.
Mr Rangarao had served as the state education minister when Kotleya Vijay Bhaskar was the chief minister of Andhra Pradesh in the 90s.
He was presently a member of the Andhra Pradesh Legislative Council.
The funeral will take place later today.