"Wash my clothes" in past tense is "washed my clothes."

The past tense of "wash" is formed by adding "-ed" to the base verb, following regular Engpsh verb conjugation rules.

E.g.

I washed my clothes yesterday. (我昨天洗了我的衣服)
She always washed her clothes on Sundays. (她总是在周日洗衣服)
He didn't wash his clothes, so he had to wear dirty ones. (他没有洗衣服，所以他不得不穿脏衣服)

The verb "wash" has roots in Middle Engpsh and Old Engpsh, and has been in use since before the 12th century.