Abstract: The resistivity of soil is a basic parameter to describe its electrical conductivity and one of the inherent physical properties of soil. The resistivity piezocone penetration test is a new kind of in-situ testing technique, which can measure the resistivity of the soil. The marine clay in Jiangsu province of China and the measuring equipments and the operation principles of the resistivity piezocone penetration test are introduced. Based on the measurements of soil resistivity and the laboratory test results, the relationship among the resistivity of marine clay, basic soil index and mechanical properties is analyzed. It is concluded that the salt content of pore fluid, clay content and plasticity index are the main controlling factors of the soil resistivity. The resistivity decreases with the increase of the salt content of pore fluid and the clay content, and there is a good exponential decay relationship between the resistivity and the two indexes. When the salt content of pore fluid is greater than 6 g/L or the clay content greater than 60%, the value of resistivity tends to be a constant. The resistivity decreases with the increase of the plasticity index of soil with different plastic degrees. Although other characteristic indexes have a certain influence on the resistivity, the correlations between the resistivity and those indexes are not significant.