The past tense of the word Beat is Beat or Beaten. There are three forms of any verb according to English Grammer. Some words are transformed in past and past participle by adding additional words or letters such as d, ed, and so on.

Past Tense Of Beat
But some words may be unchanged after changing the tense form. All of the words form of Beat and parts of speech are given below.
Present form: Beat.
Past form: Beat.
Present Participle form: Beating.
Present Indefinite Tense: He beats / I beat.
Present Continuous Tense: He is beating.
Present Perfect Tense: He has beat/beaten.
Present Perfect Continuous Tense: He has been beating.
Past Indefinite Tense: He beat.
Past Continuous Tense: He was beating.
Past Perfect Tense: He had beaten/beat.
Past Perfect Continuous Tense: He had been beating.
Future Indefinite Tense: He will beat.
Future Continuous Tense: I will be beating.
Future Perfect Tense: I will have beat/beaten.
Future Perfect Continuous Tense: He will have been beating.