The invention discloses an image sensor dead pixel detection method and device and an electronic device, and relates to the technical field of digital image processing. The detection method comprisesthe following steps of acquiring the external images acquired by an image sensor at different exposure times, performing dead pixel detection, and recording the position coordinates of the alternativedead pixels detected in each external image; comparing the position coordinates of the alternative defective pixels in the external images at different exposure times, and if the ratio of the numberof the external images of the alternative defective pixels with the same position coordinates to the total number of the external images is not less than a preset proportion threshold, determining that the alternative defective pixels with the position coordinates are the actual defective pixel pixels in the image sensor. According to the invention, the defective pixel detection is carried out onthe images collected at different exposure times, then the suspected defective pixels detected at different exposure times are compared, and the alternative defective pixels are further screened by setting a proportion threshold, so that the accuracy of the defective pixel detection is greatly improved.