A data serializer, a latch data device using the same and a controlling method thereof are provided. The data serializer includes at least one data buffer and a de-skew buffer. The data buffer at least receives an inputting data and a controlling signal. An outputting signal and a complementary outputting signal, which is complementary to the outputting signal, are formed when the controlling signal is at a predetermined level. The de-skew buffer receives the complementary outputting signal to accelerate or slow down forming the outputting signal.