Please be aware that Shanghai has multiple airports and that these results are for all airports serving the city.
The best day to arrive at Shanghai is Monday and it would be best to avoid Wednesday, as prices are on average 26.44% higher than on Monday. (Average prices, based on 202 datapoints.)
The cheapest airline flying from Shanghai to Hong Kong is Hong Kong Airlines. They are 15% cheaper than Cathay Pacific. (Average prices, based on 211 datapoints.)
The best time to fly is at around 18. (Average prices, based on 373 datapoints.)