The utility model discloses an internal thread type filter screen device of a kelly saver sub of a top drive system. The internal thread type filter screen device of the kelly saver sub of the top drive system comprises a lengthened kelly saver sub (1) and a filter screen (2), an axial through hole (3) is formed in the lengthened kelly saver sub (1), the upper end and the lower end of the lengthened kelly saver sub (1) are provided with an internally threaded end (4) and an externally threaded end (5) respectively, internal threads (6) are arranged in the through hole (3) of the lengthened kelly saver sub (1), a filter screen frame (7) is fixedly arranged at the upper end of the filter screen (2), the filter screen (2) is arranged in the through hole (3), and the filter screen frame (7) and the internal threads (6) are matched in a threaded mode. According to the internal thread type filter screen device of the kelly saver sub of the top drive system, the filter screen is arranged in the kelly saver sub, a drill pipe cannot influence arrangement of the filter screen, and therefore drilling liquid of the drill pipe without an inner step is filtered. The internal thread type filter screen device of the kelly saver sub of the top drive system is simple in structure, convenient to machine, low in input cost, remarkable in economic benefit, good in application prospect and capable of being widely applied to the field of offshore and land oil and gas field engineering.