Canada's Felix Roussel won the event on Sunday, outracing Niewiński in the final.
Britain's Niall Treacy came in third.
The 21-year-old Pole clocked in at 1:25.480, while Roussel finished in 1:25.352, with Treacy posting a time of 1:25.598, Polish state news agency PAP reported.
Niewiński's second place in Beijing marks his second podium finish this season, after a bronze in the 500m in Montreal.
The World Tour is an elite series of short-track speed skating events in North America, Asia and Europe.
(gs)
Source: PAP