The coastal zone imager carried by the HY-1 C/D satellite uses high-resolution linear pushbroom cameras, which can obtain remote sensing data with a resolution of 50 m. Realizing in-orbit geometric positioning of its images and obtaining standard image products is the foundation for subsequent remote sensing data applications. In this paper, according to the physical structure and imaging mechanism of the instrument, a strict geometric imaging model of remote sensing image of the coastal zone imager is established. We create the coordinates of the observed vector in the focal plane system under ideal conditions, and optimize the traditional geographic coordinate conversion process. The ground preprocessing experiment was conducted using real-time level 0 data received by the ground station, and the system error compensation was performed using the lake inflection point error. The results showed that the average accuracy of the positioning results obtained by the method in this paper is less than one pixel, and the positioning performance in mid to low latitude areas is slightly better than that in high latitude areas. It indicates that this method can meet the basic positioning accuracy requirements, and realize the ground target positioning of HY-1 C/D coastal zone imager images in uncontrolled areas.