Kylian Mbappe and Edinson Cavani were on the scoresheet in the win that came in oppressive heat at the Suzhou Olympic Sports Centre.
Mbappe opened the scoring with a terrific 37th-minute finish and Cavani doubled the lead just before the break.
Metehan Guclu added a third in the 89th minute to round off things off for PSG, who open their season in just five days against Rennes in the Trophee des Champions.
Neymar was not involved, remaining at PSG's training base in Shenzen, but Thomas Tuchel still named a strong side that included new signings Ander Herrera, Pablo Sarabia and Abdou Diallo.
Cavani was denied a 13th-minute opener after Sydney FC goalkeeper Andrew Redmayne tipped the Uruguayan's effort onto the post but the A-League side acquitted themselves well in the opening half hour.
Sydney then had the ball in the back of the net but Milos Ninkovic's tap-in was disallowed after Rhyan Grant - who headed the ball across the face of goal and through the legs of PSG goalkeeper Kevin Trapp - was offside from a free-kick.
The 36th-minute incident was like poking a tiger, PSG stirring to score twice before the break.
Mbappe provided the first, playing a neat one-two with Juan Bernat before thrashing a left-footed effort past Redmayne despite the tight angle.
And Cavani was on hand to turn in the second, pouncing on the rebound after Sarabia's effort was saved following excellent build-up work by Julian Draxler.
Tuchel made 10 substitutions for the second half and one of his changes, Adil Aouchiche, twice forced Redmayne into a save, while he also went close from a free-kick.
A combination of the heat and the substitutions saw the match fizzle out but there was still time for Guclu to strike, the Turkey youth international producing a neat flick to turn Colin Dagba's cross in.