Refuse extry to singapore

You didn't tell your status in Singapore, are you a foreigner? If yes then are you holding work pass or any other related pass? Why can't you sponsor your wife?

Please be noted that this is a public forum and no one will take responsibility to undertake and sponsor your wife. You should find someone whom you know here can do this.

Im singaporeans and im the sponsors she have a police case in witness

If she has a police case, this is most probably the cause of the ban. Work with the police/courts to get the matter cleared!
(Another possibility that could cause such problems is if she ever held a WP before, and you didn't see permission from MoM before marrying her.)

Knowing how long is the ban?

Guyneedhelp18 wrote:

Knowing how long is the ban?

Yes, that's also something you should work with ICA about.

Vietnamese do not require VISA to enter Singapore, You know you wife well???
Could it be she has not disclose her full information to you??
I am married with a Vietnamese wife as well, she got her LTVP without any problem, PR status after 9 months, and we fly back and almost every 2 months, sometime staying few weeks to 2 months in Vietnam and other country.
Immigration never raise question. Only time was during the first month, we went for short trip after getting the Visa Extension pending LTVP, was stop at reentry and went into their office for 2 hours or so, as during VISA extension, she was not suppose to leave Singapore..... but was allowed to enter after explanation that we were not aware.
So the question must be your wife previous status in Singapore..

can an s-pass holder foreigner sponsor for LTVP pass?