An image fusion method and device is disclosed, which includes: obtaining a first short-focus image and a first long-focus image acquired by a short-focus sensor and a long-focus sensor at the same time; calculating a reduction coefficient corresponding to the first long-focus image when the sizes of the same target in the first long-focus image and the first short-focus image are matched; performing a reduction processing on the first long-focus image according to the reduction coefficient to obtain a second long-focus image; according to a relative angle of the current long-focus lens and short-focus lens, calculating a position of the second long-focus image in the first short-focus image when the positions of the same target in the second long-focus image and the first short-focus image are matched; and covering the first short-focus image by the second long-focus image to obtain a fused image.