Generally, if your resume is too big, you must have pictures. In this case, it is best to compress the picture, and you can use image editing software such as PS to compress the picture. You can also use word's own compression tool: file-save as-has a "tool" in the pop-up dialog box. Click on the compressed image inside, and pay attention to the "web- screen" option -ok.

If there are too many words in word and there are no pictures, then I suggest deleting some. Generally, resumes that are too big have pictures.