Do Chinese domestic airlines have the same restrictions regarding carry-on items -3oz. liquids, etc. or can we carry our regular toiletry kit on board? Are the carry on baggage size restrictions similar to US airlines? Can my husband carry his pocket knie - small Swiis army style - or will that need to be checked?

There is no liquid rule for domestic flights. But pocket knife is not allowed. They security does a pretty thorough job for all domestic flights, so make sure you check the knife.

rkkwan, welcome home
we are hoping to travel within China (domestic flghts) with only carried-on luggage to avoid check-in bags, is there a site one can find out sizes, weight etc.
Thanks

You should really check bags on domestic Chinese flights. There's no connection, so little chance of losing baggage, and in my experience in the smaller airports, the bags come out before you get to baggage claim.

But for carryon, no one weighs your bags, and you may find size limits on the domestic airlines' site - probably 45" overall inches 22" x 9" x 14". I am too lazy to search for you.

rkkwan,

good point, tks

I disagree about liquids, there are indeed restrictions. If you are carrying water, they may ask you to take some sips. Liquids need to be separated before xray of carryon.
Another opposite: the airlines all require that you lock your checked baggage. If not, they will put a lock on it and give you a huge ring of keys to find one matching the lock.
Weight restrictions are often strictly enforced, but if you are travelling on a tour, there is no problem. You don't check your bags in individually, they go as a group, so a pound or 2 over aren't charged. Note that if on your own, they may demand weighing your checked and carryon to total the weight allowed.
Another poster was right, the luggage comes off very fast, so there is no incentive to carry on like in the U.S.
If you forget to put that Swiss knife or bottle opener in your checked luggage, they will provide a box and check it separately for about $3.

I took 4 domestic flights last fall. I don't have a lock on my luggage. Of the 4 times, nobody noticed for 3. On the 4th time, the check-in agent mumbled something, but still took it.

But they DO expect all checked bags to be locked.