The strength of reinforced concrete pile is largely controlled by the steel reinforcement inside the pile. Finding an effective way to determine the length of the steel reinforcement in bored in situ concrete piles has been an urgent but difficult problem for the construction administration agencies in China. Taking advantage of the significant difference in the electrical conductivity between the steel reinforcement and the concrete pile body, we apply the mise-a-la-masse (MALM) method, which has traditionally been used in ore exploration and coal mining, to determine the reinforcement length of bored in situ concrete piles. Preliminary tests show that the voltage (electrical potential) curve sharply increases at the bottom of the steel reinforcements, where the voltage gradient curve also peaks. Thus, the MALM method could be an effective, fast and convenient way to determine the reinforcement length in bored in situ concrete piles. The MALM method may also be used in the survey of old steel piles, bridge footings and dam foundations whose configurations are not available.