The utility model discloses a multiple channel weak signal acquisition circuit and a time division multiplexing circuit thereof. The multiple channel weak signal acquisition circuit comprises multiple transmission channels, an amplifying circuit and the time division multiplexing circuit which is arranged between multiple transmission channels and the amplifying circuit. The time division multiplexing circuit comprises a time base circuit which is used for generating a time base signal, an input gating circuit which is used for choosing to output electrical signals of multiple transmission channels to the amplifying circuit one by one, and a control circuit which is used for converting the time base signal into a control signal which controls the input gating circuit to choose to output the electrical signals of multiple transmission channels one by one. The control circuit is respectively connected with the time base circuit and the input gating circuit. According to the time division multiplexing circuit, the defects caused by multiple channels which acquire weak signals can be effectively avoided; noises caused by a weak signal acquisition process are reduced; the circuit load capacity is improved; the space cost of the multiple channel weak signal acquisition circuit is saved; and the routing efficiency is improved.