Based on the finite element model of high-pressure jet grouting piles composite foundation,when the arrangement forms of high pressure jet grouting pile with low intensity are equilateral triangle and equilateral quadrilateral,we study the influences of elastic modulus of pile,internal friction angle of soil,and length of pile on the bearing characteristics of composite foundation,and analyze the effective length of high-pressure jet grouting pile.The results show that the maximum vertical settlement value of soil with the arrangement form of equilateral quadrilateral is 93% of it with the arrangement form of equilateral triangle,the maximum vertical stress value of pile is 97% of it with the arrangement form of equilateral triangle arrangement,and the arrangement form of equilateral quadrilateral for high pressure jet grouting pile is better than the arrangement form of equilateral triangle for it.With the decrease of the elastic modulus of high pressure jet grouting pile,the maximum settlement value of soil increases,and the maximum vertical stress value of pile decreases.With the increase of the friction angle of soil,the maximum settlement of soil decreases,and the maximum vertical stress value of pile also decreases.The maximum vertical stress vertical of pile with the arrangement form of equilateral quadrilateral and equilateral triangle is basically unchanged when the length of pile is more than 10 m,so the effective length of high-pressure jet grouting piles with low intensity is about 10 m,and it is consistent with the results of the literature and the design values.