The invention discloses an MEMS straight-pulling straight-pressing two-axis accelerometer chip and a preparation method thereof. The accelerometer chip is manufactured by adopting an SOI silicon waferand is formed by arranging four identical sensor sub-units around the center of the chip, wherein each sub-unit comprises mass blocks, support beams, sensitive beams, a hinge beam, wires and bondingpads, the mass blocks are connected with a chip frame through the support beams, two mass blocks are connected through the hinge beam, two sensitive beams are symmetrically distributed at two sides ofthe hinge beam, the wires are connected with the bonding pads to form a semi-open-loop Wheatstone full bridge circuit; and the chip frame is bonded on a bottom glass plate. One group of sensor sub-units measures the acceleration in the x-direction, and the other group measures the acceleration in the y-direction. The accelerometer chip can achieve separated measurement for two-axis acceleration below 100g, the intrinsic frequency is greater than 25kHz, the sensitivity is greater than 0.9mV/g/3V under an amplification-free condition, and the accelerometer chip has good performance.