Soil surface charge was measured with the potentiometric back-titration technique, and its characteristics evaluated with the Multi-Langmuir model. Results show that the variable surface charge of yellow soil and yellow brown soil varied in the range of 0~45 cmol kg^-1, of red soils in the range of 0~22 cmol kg^-1 and of latosolic red soil and latosol in the range of 0~14 cmol kg^-1, depending on pH of their respective soil suspension. The multi-Langmuir model was used to simulate surface charge, assuming that the three-site model might be adopted to describe the relationship of variable charge with pH. Of yellow soil, yellow brown soil, Hunan red soil, Jiangxi red soil, latosolic red soil and latosol, pK¹ was 4.45, 4.46, 4.76, 4.62, 4.66 and 4.74, respectively; and Q^v1 was 11.65, 9.64, 9.31, 7.14, 4.86 and 5.95 cmol kg^-1 respectively. Yellow soil and yellow brown soil was about 0.3 lower than red soil, latosolic red soil and latosol in pK¹. An extremely significant linear correlation of pK¹ with ZPC was observed and so was an extremely significant positive correlation of Q^v(i) with organic matters.