Single-load hydraulic system and machine

The invention relates to a hydraulic system (10) used for a machine. The hydraulic system comprises a hydraulic steering system (11), a working hydraulic system (12), a variable pump (14) and a metering pump (16), wherein the variable pump (14) is used for supplying hydraulic fluid for the hydraulic steering system, and the metering pump (16) is used for supplying the hydraulic fluid for the working hydraulic system; the variable pump is selectively in fluid communication with the hydraulic steering system and the working hydraulic system through a priority valve. The hydraulic system is characterized in that the priority valve is provided with an LS port (133); the LS port is used for receiving a load feedback pressure signal (LS) from the hydraulic steering system when the hydraulic steering system works, and moreover, the priority valve is structured to supply the hydraulic fluid pumped by the variable pump to the hydraulic steering system preferentially when the hydraulic steering system works.