A method for data transmission in a TDD system is disclosed. The method includes: configuring, by a base station, a length respectively for a Downlink Pilot Slot (DwPTS) and an Uplink Pilot Slot (UpPTS) within a special field of a radio half-frame based on a current coverage area taking one Orthogonal Frequency Division Multiplexing (OFDM) symbol as a unit, and issuing a configured result to a user device, wherein a total length of the DwPTS, a Guard Period (GP) slot and the UpPTS is kept to be 1 ms; constructing, by the base station, radio half-frames for data transmission according to the configured result. An apparatus for data transmission in the TDD system is also disclosed. According to the present invention, coverage area of different levels with smaller granularity is supported, radio resources are saved and transmission efficiency is increased.