The invention discloses an MEMS pressure sensor chip based on an SOI technology and a manufacturing method of the MEMS pressure sensor chip. The MEMS pressure sensor chip is suitable for absolute pressure measurement and comprises a monocrystalline silicon substrate. A flat elastic membrane is arranged on a groove of the monocrystalline silicon substrate. The edge of the elastic membrane is provided with corrosion holes. The elastic membrane and the groove of the silicon substrate form an airtight cavity. Four monocrystalline silicon strain resistors are arranged on the elastic membrane. All the monocrystalline silicon strain resistors are isolated from one another through insulating media, and the monocrystalline silicon strain resistors are also isolated from the elastic membrane through insulating media. The four strain resistors are connected through metal wires to form a Wheatstone bridge so as to convert pressure into a voltage and output the voltage. The MEMS pressure sensor chip has the advantages of being small in size, good in repeatability and hysteresis, high in sensitivity, wide in operating temperature range, and the like; besides, the manufacturing technique is compatible with the integrated circuit technique.