When the vibroflotation method is used to treat the fine sand foundation，the construction process and construction parameters have a great influence on the final foundation treatment effect.This paper carries out field vibroflotation tests with different construction parameters for dry，loose，and fine sand in a port project in Peru，South America and conducts standard penetration tests to compare the density changes of the dry，loose，and fine sand at different positions before and after vibroflotation.When dry，loose，and fine sand is reinforced，the traditional vibroflotation process has the problem of insufficient density at the top.Therefore，this paper analyzes the causes of the defects and puts forward the construction improvement measures of “partial filling，timely backfilling，water pressure reduction，and layered counter-insertion”.The results show that the improved vibroflotation construction process can effectively reinforce the loose backfill fine sand.