The collimator response compensation is very important in high-resolution pinhole SPECT imaging for resolution recovery and quantitative imaging. In this study the pinhole collimator response of the keel-edge aperture was investigated in terms of the geometric response function and penetration response function (GPRF). An approximate numerical method was proposed to implement the geometric and penetration response correction (GPRC) for keel-edge pinhole SPECT image reconstruction. A lookup table for the GPRC was calculated and then was utilized in the 3D pinhole iterative OSEM reconstruction procedure. The performance of the image reconstruction with the GPRC was evaluated using both the phantom and small-animal experiments in our micro-SPECT system. The results demonstrated significant improvements in the reconstructed image quality and resolution recovery. In conclusion, our approach using the GPRC method to the resolution recovery for the pinhole SPECT imaging is effective.