Abstract: The software package HOTPANTS is an important tool for astronomical image subtractions. It plays important roles in observation of transit planets, observation of gravitational lensing, supernova search, and discoveries of new astronomical phenomena. However, the original HOTPANTS package which is based on CPU processing is not suitable for processing massive real-time astronomical data. We analyze the problems limiting the performance of the HOTPANTS and modify it to be based on CUDA-GPU processing. The modified HOTPANTS package is 9 to 13 times faster than the original HOTPANTS package in performing image convolution. Efficiencies of complete image processing are improved by 2 to 3.5 times with the modified package. Our error analysis shows that results from the modified package are of acceptable accuracies like those from the original package.