The friction thermal deformation of guide rail during the reciprocating movement of linear guide rail was simulated. Considering the relative position between the guide rail and the slider, the influence of frictional heat on the thermal deformation of linear guide rail during the roundtrip movement was analyzed.The thermal load distribution of the linear guide pair was analyzed,the thermal strain finite element model was established, and the guide rail deformation under the load friction heat source was calculated.It provides guide for thermal error compensation in machining process.