Abstract: The p-y curve method of pile-soil dynamic interaction is widely used in geotechnical engineering. A simplified analysis model of soil-single pile-cap interaction is set up by using p-y element through the embedded Pysimple1 material model of the Opensees software. The dynamic response characteristics of pile and pile cap in p-y element of sandy soil and clay soil were researched and the dynamic response of pile body and pile cap under different length of free field were analyzed. The results show that the peak acceleration of pile cap in the p-y element of sand soil is larger than that of the clay element, while the peak displacement is less than the clay element. The pile shearing force, bending moment and acceleration in the p-y element of sand soil are stronger than those of the clay element. The shorter the free field length is, the greater the displacement and acceleration of pile caps are. The requirement of calculation accuracy would be satisfied when the free field length reaches 300 m.