The electrical resistivity of liquid PbSnBi alloy has been precisely measured by the Direct Current (DC) four-probe technique in our experiment. It was found that the electrical resistivity-temperature (ρ-T) curves changed discontinuously at several-hundred degrees above liquidus. However, the ρ-T curves was linear before this turning point with increasing temperature. Moreover, the ρ-T curve of the different composition alloys showed different turning points. The anomalous behavior of electrical resitivity indicates the alteration of the electron transport properties and the mean free path LZ of conduction electrons, since resistivity as one of the physical properties sensitive to the structure and this discontinuous alteration induced by temperature suggests the liquid-liquid structural transition taking place in PbSnBi melts. This present Letter makes a beneficial attempt at studying electrical resistivity to investigate liquid-liquid structural transition.