HongKong - Shanghai(Flight) -- Shanghai - Beijing - Shanghai(train) -- Shanghai - HongKong (flight)

Hi, I'm flying into Shanghai from Hong Kong (31st Aug) and spending one day in Shanghai. I've planned to take the train to Beijing from Shanghai (1st Sept) and spend two days in Beijing then take the train back to Shanghai (3rd Sept). I fly out of Shanghai (3rd Sept) back to HongKong. I have a Canadian passport and travel time is within the 72hrs free travel. Is this planned itinerary possible with the train between Shanghai and Beijing without a travel visa for China?