A computer-assisted needle insertion system and a computer-assisted needle insertion method are provided. The computer-assisted needle insertion method includes: obtaining a first machine learning (ML) model and a second ML model; obtaining a computed tomography (CT) image and a needle insertion path, generating a suggested needle insertion path according to the first ML model, the CT image, and the needle insertion path, and instructing a needle to approach a needle insertion point on a skin of a target, wherein the needle insertion point is located on the suggested needle insertion path; obtaining a breath signal of the target, and estimating whether a future breath state of the target is normal according to the second ML model and the breath signal; and outputting a suggested needle insertion period according to the breath signal in response to determining that the future breath state is normal.