The invention discloses a battery connection device comprising a connection block positioned at an electrode end of a battery; the connection block is provided with a series connection mechanism at both ends respectively, and with a parallel connection mechanism at all sides respectively; the series connection mechanism is provided inside with a conductive slice electrically connected with the electrode end of the battery; the conductive slice is further led out to a fitting face of the parallel connection mechanism; and thus the conductive slices on the two connection blocks are electrically connected when the two batteries respectively fitted with the connection block are parallel. The invention can make each unit battery connected modularly in series or parallel like a building block; the battery does not further need electrode connection by welding or battery fixing by assembling, which is convenient for operation as well as safe and reliable.