The Canadian husband has to sponsor her for permanent residency. Canada immigration will not give any kind of temporary visas to people they don't think are going to leave again when the visa expires. A person applying for a temporary visa who is married to a Canadian is considered a risk to overstay. If they can prove they have ties to their homeland and will return there after their visit to Canada, they might be able to get a visit visa. It's harder in some embassies than others. Of course this does not apply to people who are from visa exempt countries because they don't need a visa to go to Canada.
When a Canadian files an application to sponsor a spouse who is living in another country (called outland), it first goes to Mississauga to approve the sponsor. Somebody may be declined to sponsor because he's been on welfare, has a criminal record, is still bound by a sponsorship agreement to a previous spouse etc. Right now this part is taking 43 days, see http://www.cic.gc.ca/english/information/times/canada/process-in.asp#sponsorship After that, the file goes to the local visa office in the country of the spouse and you can see different processing times here: http://www.cic.gc.ca/english/information/times/international/05-fc-spouses.asp For China right now, it's 3-5 months.
There is also another process to sponsor a spouse that is in Canada (called inland) but it has some disadvantages. You can always pick the outland option, regardless of if the spouse is in Canada already or not.