In order to reduce the effect of resolution reduction and mismatch between units caused by traditional interpolation method on division of focal plane polarimeter, a method of polarization information based on convolution interpolation was proposed. The labeling and convolution interpolation method was studied to extract the polarized image, thus to compute the polarization. Then, the detection system was calibrated by least square method. After calibration, the error of degree of polarization is less than 2.5% and error of angle of polarization is less than 0.25°. Finally, the proposed interpolation method was used to image in different occasions by changing differnet detectors and micro polarization arrays. The exprimental results show that the proposed method can effectively reduce the effect of resolution reduction and be well adapted to the modular division of focal plane polarimeter.