In order to meet the demand of measuring liquid pressure in narrow chamber, this paper designs a non-contact Fabry-Perot microcavity based optical liquid pressure measuring system. The optical microcavity is fabricated by two-photon 3D printing technology, with a compact size of 350 μm. The diaphragms with a thickness of 4 μm and 6 μm were designed. The system is based on combination of the embedded design and diffraction grating spectral module, which can acquire the optical interference signal, realizing high-resolution spectrum dynamic demodulation. The experiments show that the sensing sensitivity of the 4 μm-thickness device can reach 398 pm/kPa at room temperature (25 ℃), and the system shows a high resolution of 35.5 Pa and good repeatability, which has potential in biomedical intraocular pressure sensing applications.