In-situ collection device and method of soluble substance

The invention discloses an in-situ collection device and method of a soluble substance. The in-situ collection device of the soluble substance comprises a bracket, a microporous ceramic sampling headand a sampling pipe, wherein the microporous ceramic sampling head is tubular, and the microporous ceramic sampling head is fixed on the bracket and is used for in-situ collection of the soluble substance; and the sampling pipe is connected with the microporous ceramic sampling head and is used for conveying collected objects in the microporous ceramic sampling head. In-situ collection of the soluble substances in samples with different depths is realized by using the microporous ceramic sampling head and the bracket so that online analysis and real-time monitoring of target substances are realized by further combining an online analysis instrument. Particularly, for in-situ sampling of soil with a low water content, the invention provides an in-situ injection-in-situ desorption-in-situ extraction sampling method