hi , canadian to HK but stay in shanghai in the fisrt 144 hours

You can use 144 hour visa free transit, but just for one transit area. You will have to choose whether it will be Shanghai or Beijing. You cannot visit both Shanghai and Beijing. In other words, an eligible itinerary is:

Toronto - Shanghai - Hong Kong

but

Toronto - Shanghai - Beijing - Hong Kong

Is not eligible.

Simply speaking, you cannot have two mainland Chinese stops in a row of any kind.