Disclosed are a hydrostatic system, a hydrostatic steering system and a hydrostatic pressure-limiting oil replenishing device thereof. The hydrostatic system comprises a plurality of hydrostatic hydraulic cylinders and the hydrostatic pressure-limiting oil replenishing device, the hydrostatic steering system comprises a steering signal cylinder, a steering actuation cylinder and the hydrostatic pressure-limiting oil replenishing device, the hydrostatic pressure-limiting oil replenishing device comprises a cylinder body, a piston component and an elastic component, the piston component is mounted in the cylinder body, the elastic component is used for balancing total pressure of hydrostatic chambers of the hydrostatic system and connected with the piston component, the piston component comprises multiple pistons and a piton rod, the piston rod is used for connecting the pistons, each piston divides an internal space of the cylinder body into a containing chamber and an oil storage chamber which are positioned on two sides of the piston, the containing chamber and the oil storage chamber between two adjacent pistons are spaced by a spacing sleeve, and the multiple oil storage chambers are communicated with the corresponding hydrostatic chambers of the hydrostatic system respectively. By the hydrostatic pressure-limiting oil replenishing device, operability and reliability of the hydrostatic system are improved greatly.