The invention provides a soil heavy metal volt-ampere detection method adopting two steps of electric deposition and dissolution. The method comprises the following steps: (1) adding bismuth ions into a soil leaching liquor, and by taking a graphite powder-paraffin oil carbon paste electrode as a working electrode, plating a bismuth film on the electrode by adopting an in-situ film plating method; (2) forming a carbon paste three-electrode sensor through the graphite powder-paraffin oil carbon paste electrode, and performing primary deposition on heavy metals in the soil leaching liquor to be detected through a dissolution volt-ampere method for 500 to 1,000 seconds; (3) dissolving out the heavy metals deposited on the surface of the electrode into an electrolytic tank through the dissolution volt-ampere method; (4) placing a glass-carbon three-electrode sensor consisting of a multi-wall carbon nano tube-Nafion modified glass-carbon electrode into the electrolytic tank, and performing secondary deposition and dissolving out on heavy metal ions in the electrolytic tank, thus obtaining a heavy metal dissolution volt-ampere signal. The soil heavy metal volt-ampere detection method is high in portability, easy to carry and operate, low in cost and wide in detection range, and can be widely applied to actual detection of all fields.