The dilatometer method for density measurement of liquid metals was improved to give a high measurement accuracy with simple operation. The density of liquid tin was measured and the results are in agreement with values in literature. The melting point density of liquid Sn was measured to be 6.966×10^3 Kg·m^-3 and the temperature （T） dependence of the density （p） for liquid Sn can be well described by a polynomial equation p（T）=7.406 - 9.94 × 10^-4T ＋ 2.12 × 106-7T2.
