A tea brewing device, having a cup body, a tea leaf chamber, and a top cover connected with the cup body; a tea leaf chamber separation mechanism is provided at the top cover, containing a sliding block and a separation magnet protruding out of a bottom side of the sliding block; the sliding block changes its position relative to the top cover by sliding; the tea leaf chamber is disposed inside with a sealed magnetic metal; the tea leaf chamber is attracted to a bottom side of the top cover via magnetic attraction between the separation magnet and the magnetic metal; the sliding block is driven to slide so that the separation magnet is moved away from the magnetic metal, and the magnetic attraction between the two becomes weaker than a gravitational force of the tea leaf chamber, which then drops down to the cup body, thereby beginning tea brewing.