The move comes less than two weeks after the PiS government lost a diplomatic campaign to oust Tusk.
Defence Minister Antoni Macierewicz and many other members of the governing Law and Justice (PiS) party have long insisted the crash was no accident, even though both Polish and Russian investigators found that pilot error, bad weather and poor air-traffic control were to blame.
The then-president Lech Kaczynski -- the twin brother of PiS leader Jaroslaw Kaczynski -- and many senior state officials died when the plane came down in Smolensk, western Russia on April 10, 2010.
Macierewicz claims Tusk, the prime minister at the time, committed treason "in connection with the investigation into the causes and circumstances of the Smolensk crash", a spokeswoman for the prosecutor's office, Ewa Bialik, told AFP.
Treason is punishable by up to 10 years in prison.
The move comes less than two weeks after the PiS government lost a diplomatic campaign to oust Tusk from his current post as European Council president, a move which isolated Warsaw within the EU.
Macierewicz, who believes the crash was the result of a Polish-Russian conspiracy, has notably slammed Tusk for failing to recover the wreckage of the plane from Russia.
He claimed in an interview with the nationalist daily Gazeta Polska Codziennie that Tusk "had reached an illegal agreement with (Russian President) Vladimir Putin to the detriment of Poland."
In November 2016, Polish justice officials began exhuming the remains of the victims to test for traces of explosives or combustion, as the PiS believes a fire may have started on board before the plane went down.
The crash occurred as the presidential delegation was heading to a ceremony in Russia's Katyn forest for thousands of Polish army officers killed by Soviet secret police in 1940 -- a massacre the Kremlin denied until 1990.