The invention relates to the field of fuel injection devices and control, in particular to a marine dual-fuel / gas engine multipoint multi-stage injection system. The marine dual-fuel / gas engine multipoint multi-stage injection system comprises an air cylinder, an intake valve, an intake manifold, an exhaust valve, an exhaust manifold, a gas collector, an injection valve block, a pressure stabilizing cavity, an air rail pipe, a gas pressure sensor, a gas temperature sensor, a pressure regulator, an on-off solenoid valve, a filter, a gas storage unit, a control system and a lambda sensor. The injection valve block can be used to solve problems about development, modification and matching of dual-fuel or gas engines, gas supply requirements for high flow under high load and high revolution speed and small flow under low load of the engines can be met, gas injection control precision of the dual-fuel / gas engines is increased, fuel distribution uniformity of different cylinders is improved, and thus dynamic property, economical efficiency and emission performance of the engines are improved.