Abstract: Based on the similarity principle，a 1:2.5 water model was established for orthogonal test，and the range analysis and variance analysis of the test results were carried out. The results showed that the main factors affecting the optimization of flow field characteristic parameters were the height of the lower retaining wall and the distance between the upper retaining wall and the bottom of the upper retaining wall. The optimal combination of flow control devices was proposed: the distance between upper and lower retaining walls was 867 mm，the distance between upper and lower retaining walls was 225 mm，the distance between upper and lower retaining walls was 200 mm，and the height of lower retaining walls was 350 mm.The average total oxygen content and the occurrence rate of large inclusions were reduced by 16% and 57% respectively by using the optimal flow control device.

Key words: continuous casting, tundish, orthogonal test, water model, residence time