My wife priod day evry month 9th.we had sex without protection after 21 days that mns 30th.is ths safe to avoid pregnancy?

There is NO truly safe method except abstinence.
Failing that multiple forms of birth control will mitigate any risk.

First no, her period can not be the 9th of each month, women cycle by a number of days, 24 days, or 28 days, or 31 days, Since there is 28 days in some months, and 31 days in other months it is just not possible for her to always start on 9th of the month.

Also women's cycle each month do vary by a day or two often and sometimes even more.

Next unless she is taking medical tests to determine her ovulation time, women differ on this.

While the chances on average are less, of course she can get pregnant during those days. There is no "safe: day, some women can even get pregnant while on their period.

If you want to be "safer" she should be on birth control and you should be using a condom.