The invention discloses a mechanical and electrical piston directly-driven reciprocating pump, which mainly comprises an internal-combustion engine cylinder, a reciprocating pump cylinder, a rack rod, a rack rod clutch, a coupling, a start wheel, a starter, a crankshaft, a connecting rod, a motor clutch, a motor and the like. Pistons of an internal-combustion engine cylinder group and a reciprocating pump cylinder group are in a direct-drive mode, so that the mechanical and electrical piston directly-driven reciprocating pump not only has the characteristics of the reciprocating pump, but also is simple and compact in structure, low in energy consumption, high in efficiency and stable in flow and pressure; two powers of an internal-combustion engine and the motor can be interchanged for use, so that operation requirements for the industries of fire protection, mines and oil fields can be met, particularly the operation requirements in situations of no electric power or emergency power failure can be met.