Abstract: The bending performance of the secant piles is crucial to the design of foundation pits.The mixture ratio of ultra-retardation concrete was determined in accordance with the requirements of strength and coagulation time by laboratory tests.Through model tests,the bending performance of the secant piles with intercrossing of reinforced concrete pile(RCP) and plain concrete pile(PCP) was studied and the mechanical behavior and the effect of PCP on the bending capacity of secant piles at different stages from elastic to plastic state had been achieved.Furthermore,the bending performance of secant piles in different cases had also been evaluated through field measurement of the stress of steel and displacement of the pile.It was shown by in-situ tests that it was reasonable to take the effect of plain concrete piles into consideration in design.