A two-dimensional (2-D) accelerometer is a commonly used sensor for detecting horizontal vibrations. However, their low-frequency response characteristics are limited by high cross-axis sensitivity and low resolution. To address this challenge, this study proposes a new 2-D optical accelerometer based on a symmetric 2-D vibration pickup unit and a high-sensitivity 2-D angle sensor modified from a DVD pickup head. The parameters of the symmetrical 2-D pickup unit were determined through modeling and simulation, and the performance of the accelerometer was tested experimentally. Experimental data show that the accelerometer has good low-frequency response characteristics in the range from 1 to 10 Hz, sensitivity is better than 2.5 V/(m/ $\text{s}^{2}$ ), cross-axis sensitivity is less than 0.075 V/(m/ $\text{s}^{2}$ ), and the resolution is better than 0.4 mm/ $\text{s}^{2}$ . Moreover, the sources of uncertainty of the accelerometer were analyzed in detail, and the synthetic uncertainty of the accelerometer was analyzed based on experiments. Compared with conventional techniques in this area, the proposed 2-D optical accelerometer has featured the advantages, such as high accuracy and low cross-axis sensitivity, and can be widely used for low-frequency vibration monitoring in engineering applications.