The invention discloses a hydraulic control system and a hydrostatic testing steel pipe machine oil-water balance system with the hydraulic control system. The hydraulic control system comprises multiple master cylinders, a constant pressure variable pump, a proportional pressure reducing valve, a proportional overflow valve, an electromagnetic overflow valve, a prefilled valve and a top petrol tank. The multiple master cylinders are connected in parallel. The constant pressure variable pump is driven by an electrical machine. The inlet of the constant pressure variable pump communicates with the top petrol tank. The outlet of the constant pressure variable pump communicates with the master cylinders. Each of the electromagnetic overflow valve and the proportional overflow valve is arranged between the constant pressure variable pump and the top petrol tank in a communicated mode. The proportional pressure reducing valve is arranged in series between the constant pressure variable pump and the master cylinder. The prefilled valve is arranged between the top petrol tank and the master cylinder in a communicated mode. Pre-sealing compress water filling is carried out towards the testing steel pipe by the proportional pressure reducing valve. The pressure of pre-sealing is stable and the controlled pressure is small. Pressure maintaining is carried out towards the master cylinder by the proportional overflow valve so that the pressure following is stable and reliable and the responsive time is short.