The 2020 South Dakota Democratic presidential primary took place on June 2, 2020, as one of eight delayed and regular primaries on the same day in the Democratic Party primaries for the 2020 presidential election. The South Dakota primary was a semi-closed primary, with the state awarding 21 delegates to the 2020 Democratic National Convention, of whom 16 were pledged delegates allocated on the basis of the primary results.

Presidential primaries and caucuses were organized by the Democratic Party to select the 3,979 pledged delegates to the 2020 Democratic National Convention held on August 17–20 to determine the party's nominee for president in the 2020 United States presidential election. The elections took place in all 50 U.S. states, the District of Columbia, five U.S. territories, and through Democrats Abroad, and occurred between February 3 and August 11.