On tidal flats, tidal creeks are the important microlandform which varies greatly. The sediments of tidal flats usually are altered or destroyed by lateral migration and sway of tida! creeks, which affects the stability of tidal flats. Therefore, studying tidal creeks and their sediments is very useful for exploiting tidal flats, carrying out coast engineering projects and analysing ancient tidal creeks and tidal sediments.At home and abroad there are a lot of papers and works dealt with tidal creeks and sediments therein, however, genetic classification of tidal creeks and factors affecting their development haven’t been yet studied comprehensively. This paper discusses these aspects based on data obtained from literature and field observation.According to the principles of genetic classification, the tidal creeks in the world can be classified as follows:1. Tidal creek scoured by the currents on tidal flatThis is the creek which develops on the surface of tidal flat and is similar to the gully developed on mountain slope in development mechanism.2. Tidal creek scoured by the converged tidal currents.This is the creek formed by tidal currents which were locally concentrated or focused.3. Tidal creek inheriting the runoff from landAn inheriting tidal creek it the creek which originally inherited the rill formed by the small-scale runoff from land to tidal flat and then became tidal creek under the erosion of ebb- and flood-tide currents.4. Tidal creek scoured by the tide currents between lagoon and open sea.This is a kind of creeks which is relatively large and connects the lagoon with the open sea.In different parts of the world tidal creeks develop very differently. The main factors affecting the development of tidal creeks are as follows:(1) Tidal range.(2) The width of tidal flat and its relief.(3) Vegetation.(4) Mud content of sediment of tidal flat.(5) The rate of sedimentation.(6) The process of ebb- and flood-tide currents.(7) Human effect.