The present invention relates generally to the technical field of integrated circuit mask design, and more particularly to a method, an apparatus and an electronic device for photolithographic mask optimization of joint optimization of pattern and image. The method includes steps: inputting the main pattern; dividing edges of each main pattern into short edges, and regarding the short edges as a first variable for optimizing the main pattern; generating same or similar assistant feature sample points around same or similar main patterns, and regarding the assistant feature sample points as a second variable for optimizing the main pattern; and forming an objective function with the first variable and the second variable as optimization variables. The rules for generating assistant feature sample points around each main pattern are consistent, which are not limited to specific locations of the main pattern and ensures the consistency of final results for optimizing each main pattern.