Sergei Vasilievich Kuchmasov (Russian: ?????´? ?????????? ????????; born 3 August 1981 in Penza, Russian SFSR) is a Belarusian springboard diver.
Kuchmasov made his official debut at the 2004 Summer Olympics in Athens, representing Belarus.
He placed twenty-fifth in the men's springboard event, by forty-two hundredths of a point ahead of Ukraine's Yuriy Shlyakhov, with a total score of 377.61.
At the 2008 Summer Olympics in Beijing, Kuchmasov repeated his overall position in the preliminary rounds of the 3 m individual springboard event.