The invention discloses a numerical control machine tool space error modeling method based on a space grid compensation mode. The numerical control machine tool space error modeling method mainly comprises the following steps that step one, a three-axis numerical control machine tool space error universal model is established by utilizing a homogenous coordinate transformation method based on the multi-body system theory according to the type of a machine tool; step two, 21 geometric error elements in the model are measured by using a laser interferometer and modeling is performed; and step three, numerical control machine tool space error is compensated. According to the modeling method, static geometric error and dynamic thermal error modeling methods are integrated, a comprehensive model expression combination is separated into independent position influence terms and temperature influence terms, a space grid compensation list mode is adopted for the position error influence terms, and a real-time acquisition mode is adopted for the temperature error influence terms so that comprehensive compensation is realized. Therefore, the modeling method is scientific and effective and has the characteristics of being easy to compensate and convenient to apply.