The invention relates to a hydraulic camshaft and a hydraulic control system thereof. When an engine runs in a middle-high load work condition, an ECU respectively transmits four groups of switching signals to a solenoid valve according to a cam phase sensor, and the solenoid valve respectively changes the oil pressure of oil circuits which are connected with four hydraulic control parts on the camshaft according to the signals; the states of the hydraulic control parts of two adjacent cylinders are opposite; and switch is carried out at the position of a base circle in sequence by each cylinder. The hydraulic camshaft and the hydraulic control system thereof have simple and practical structure as well as two-stage valve lift, can improve the engine performance and fuel economy, and simultaneously reduce emission.