For continuous automatic, fast and high sensitive analysis of heavy metal in water by laser-induced breakdown spectroscopy technique (LIBS), the sample solution was enriched onto graphite sheet and heated by electromagnetic induction heating technology. Finally, the rapid heating and enrichment of the sample was achieved. In addition, the dry judgment method based on the cooling slope were investigated. In the example of a set temperature 140℃ and timing 2 s, the rise time was measured as 30 s from room temperature to 140℃ and the temperature error range was -5～+3℃. The completion status of enrichment was also accurately determined on the basis of the cooling slope. The results show that the rapid heating and accurate drying judgment can be effectively achieved by the use of electromagnetic induction heating technology combined with the judgment method of enrichment completion based on the cooling slope.