Dual pulse laser-induced breakdown spectroscopy (LIBS) of Ca is studied in liquid jet. The influence of the experimental conditions, including delay of integration, inter pulse delay, on the emission intensity is investigated. It is found that Ca plasma emission intensity is greatly enhanced and the inter pulsed delay time has a great impaction of emission intensity, and there is a maximum around 0.4 μs. And at this time, plasma emission time is apparently longer in dual pulse excitation than that in single pulse excitation mode. Then the calibration curves of Ca elements with different concentrations in the liquid are acquired. The limit of detection in dual pulse laser with 0.4 μs interval excitation mode is about 5 times lower than that in single pulse. The results offer feasibility and basis for the detection of metallic elements in liquid by dual pulse-LIBS.