He started to study painting in very early years at the Dresden Academy of Fine Arts under Giovanni Battista Casanova, but changed to architecture in 1791.
Thormeyer created some well known drawings depicting sights of Dresden and its surrounding, e.g. Dom Meißen, Schloss Pillnitz and Katholische Hofkirche (drawn 1807).
This reconstruction was finished in 1830, integrating the baroque city center with the surrounding and thus creating room for Dresden to grow rapidly during the following decades.
In 1814, Russian governor Nikolai Grigorjewitsch Repnin Wolkonski ordered the long-planned outside-staircase to Brühl's Terrace, Thormeyer's best-known masterpiece.
Moreover, he initiated a memorial statue of Frederick Augustus I of Saxony, finally designed by Ernst Friedrich August Rietschel.