US student applying for Cambridge. Do I need to send my SAT/AP/ACT from college board to Cambridge

I am thinking to apply for Cambridge, UK. Do I need to send my official SAT/AP/ACT from college board to Cambridge?

You should check their website! They have a whole section for international applicants:
https://www.undergraduate.study.cam.ac.uk/international-students
https://www.undergraduate.study.cam.ac.uk/usa

It appears that you would need an SAT or ACT score~

You list all scores on the UCAS form. Official score reports are only needed if admitted.

Thanks a lot. That is my understanding.

Do you know how many rec letters should i submit?

Have you read the UCAS guide to references? There are specific requirements for the content, including predicted AP scores. You should not expect to be successful with a US-style letter of recommendation, so your teacher needs to realize how much extra work this will be for them. Similarly the personal statement is very different to what you would write in the US. It is now getting very late in the day to get everything organized for the Oct 15 deadline.

@ailele, in your other post you say that you are a parent- are you asking for yourself here, or your son? CC rules are that you have to post for yourself, no sharing accounts.

Check to see if the subject that you/your son is applying to study has a pre-application aptitude test- you have to register for those by Oct 15 as well (the test date is Oct 31, and you have to get to/find a test center).