Planar capacitive sensor works based on edge effect. The sensitive field exhibits obvious soft field characteristics, as a result, its detection ability is easily affected by external factors. In order to ameliorate the sensitive field distribution characteristics and improve the sensor’ s testing accuracy, this paper proposes a new type of 12-electrode coplanar array capacitive sensor and analyzes its characteristics. First, a numerical simulation method is used to set a three-dimensional sensitive field model, and the sensitivity value three-dimensional imaging method is selected to study the sub sensitivity and the overall sensitivity distribution characteristics. Then, the evaluation index P is used to quantify the uniformity of the sensitive field distribution of the new 12-electrode sensor and the rectangular array sensor. Three different object model experiments are implemented combined with the Tikhonov regularization algorithm for image restoration. The final result indicates that the P value of the new sensor is reduced by 3. 6%, and the average correlation coefficient of the reconstructed image is increased by 7. 2%. It is comprehensively verified that the new 12-electrode coplanar array sensor effectively improves the uniformity of the sensitive field distribution, enhancing the detection capability of the sensor.