The invention discloses a preparation method of a Bi-2212 multi-core superconducting wire, which comprises the following steps: firstly, sintering Bi-2212 powder at a high temperature to obtain a tubulated precursor powder; secondly, loading the tubulated precursor powder into a silver casing to obtain a first tubulated composite body; thirdly, drawing the first tubulated composite body and assembling into a silver tube to obtain a second tubulated composite body; fourthly, drawing the second tube-tube composite body and assembling to a silver-manganese alloy tube with a silver bar to obtain athird tubulated composite body; fifthly, drawing the third tubulated composite body and performing semi-melting treatment to obtain a Bi-2212 multi-core superconducting wire. According to the preparation method of the Bi-2212 multi-core superconducting wire in the invention, the silver casing formed by lamination sleeving 2-3 silver tubes whose central lines are overlapped is used as the casing of the powder, thereby increasing the contact area between the silver and the Bi-2212 tubulated precursor powder, forming more silver super interface, obviously improving the connection between the internal crystal grains of the Bi-2212 multi-core superconducting wire after heat treatment, and improving the current carrying capacity of the Bi2212 wire.