To achieve simultaneous measurements of biochemical properties and physical structures, we proposed an endoscopic probe that combines optical coherence tomography (OCT) imaging and fluorescence ratio imaging. Based on the OCT imaging principle, the center wavelength of the OCT system was determined to be 1300 nm. Based on the absorption and reflection spectra of the selected pH indicator, the excitation wavelength of the fluorescence was determined to be 520 nm. Moreover, the basic structure of the probe was calculated and determined according to the ABCD matrix. The processing of the optical element and actual assembly of the probe were performed based on the theoretical calculation results. Furthermore, the dual-modality system was built to measure the transverse resolution and working distance of the probe. The ability of simultaneous imaging and pH detection was demonstrated on pork intestine. The probe can simultaneously perform OCT imaging and pH measurement with high accuracy. The resolution of OCT imaging in air is approximately 37.3 μm, and the working distance is approximately 13.4 mm. Moreover, the proposed system can measure the pH value of 0.01 units.