The invention relates to a hydraulic system and provides a load simulation valve and loader variable system to overcome the defect that the pressure difference between inlet pressure of a load sensitive valve and a load pressure collected by the load sensitive valve in an existing load sensitive variable system is large. The system comprises a steering hydraulic system and a work hydraulic system.The steering hydraulic system comprises a steering variable pump, a priority valve, a steering device, a steering oil cylinder and the like. The work hydraulic system comprises a work variable pump,a distribution valve, a hydraulic executing part, a pilot valve, a shuttle valve set and the like. When a pilot handle acts, load signals collected on the distribution valve are transferred to a firstload simulation valve connected to a bypass from the steering pump to the distribution valve and a second load simulation valve connected to a bypass from the work pump to the distribution valve, thedifference between action areas of two pressure differences on the load simulation valves is utilized for amplifying the pressure difference of load pressure collected by the pump and the distribution valve, finally the amplified pressure difference acts on the flow control valve of the pump, and variable control of the system is achieved.