The invention provides a double-movable blade thread cutting device of a sewing machine. The double-movable blade thread cutting device comprises a first movable blade and a second movable blade bothmovably mounted on a needle plate, and further comprises a first drive source, a second drive source, a first drive assembly and a second drive assembly, wherein the a first cutting edge of the firstmovable blade is engaged with a second cutting edge of the second movable blade, the first drive source is connected with the first movable blade through the first drive assembly to drive the first movable blade to move, and the second drive source is connected with the second movable blade through the second drive assembly to drive the second movable blade to move. Two independent drive sources respectively drive the first movable blade and the second movable blade to move, and no linkage exists between motions of the first movable blade and the second movable blade, so that the device can achieve good adjustability and controllability and can cut short thread ends stably.