Hi, Yong Hong,
Thanks for your message left to us.
Generally speaking, travelers to China, just need to offer a PCR test negative result valid within 48 hours before the departure time.
You flight to Beijing is from Geneva on March 3 and transit visa Stockholm for 2.5 hours, then arrive in Beijing in the morning of March 4th.
I suggest you take a test on March 2th after 09:30 and make sure to get the result before departure, there will be no problem. No need to do the 2nd test at Stockholm.
Please keep the printed test report in case of a random inspection at the Customs.