The invention aims to provide a directly operated type natural gas injection solenoid valve of a dual-fuel engine. The directly operated type natural gas injection solenoid valve comprises parts consisting of a connector, a rolling linear bearing, an armature, a rear casing, a magnetic conductive casing, a coil, a coil support, a bearing seat, a spring, a front end cover, a center shaft and the like. A coil winding 6 is powered on by direct current, then electromagnetic force is generated between the magnetic conductive casing and the armature, the armature is pulled in, the valve is switched on, and gas feeding is started; after the coil winding is powered off, the electromagnetic force is disappeared, the armature returns to the original position under the action of the spring tension, the valve is switched off, and the gas supply is stopped. According to the device, the valve is controlled to be switched on and off through movement of the central shaft under the driving of the electromagnetic force, the structure is quite compact, the intensity of the central shaft is higher, the response speed is high, and the work is safe and reliable.