Please be aware that Beijing has multiple airports and that these results are for all airports serving the city.
The best month to fly between Beijing and Guangzhou is August and the most expensive month to fly is March. (Average prices, based on 215 datapoints.)
The best day to arrive at Beijing is Monday and it would be best to avoid Friday, as prices are on average 67.74% higher than on Monday. (Average prices, based on 414 datapoints.)
The cheapest airline flying from Beijing to Guangzhou is China Eastern Airlines. They are 51% cheaper than Air China. (Average prices, based on 223 datapoints.)
The best time to fly is at around 8. (Average prices, based on 241 datapoints.)