For the local scouring problem caused by the tidal current flow of piletype buildings such as bridge piers in the estuary area，the physical model is adopted in this study to reveal the mechanism process of local scouring of piers caused by tidal currents and the morphological changes of local scouring pits. The test results show that the local shear stress of the pier is gradually attenuated during the local scouring process of the pier，and the tidal current causes a large bed shear stress. However，due to the short acting time，only a large amount of sediment is started in the initial stage，and in the subsequent stage of fast water，the local scouring of the bridge pier is rapidly developed. The greater the tidal bore intensity and Froude numbers of the tidal height，the stronger the local scouring of the pier. For bridge piers of square shape，in the develop process of local scouring pit，the stronger vortex structure is triggered by the higher shear strength of tidal bore，which makes the water surface flushing more intense than the side flow scouring. The rounded piers have little difference in the water surface and side scouring. Meanwhile，the square piers in the asymmetric rotation scouring have a more scouring depth than that in the symmetric rotation scouring. After the multivariate regression analysis of test data，the comprehensive calculation formula of the local scour of pier caused by the tidal tide is obtained. The formula shows that it has better prediction accuracy and the maximum error with the test value does not exceed 12%.