Precision and precision retaining ability are core indicators of performance of high precision machine tool. Guide pair works as the core part of feed system of machine tool and it decides the machining quality and precision of workpieces. Slide guide is one kind of the most frequently used guide pair of machine tool. It is a typical sliding friction system and definitely wear is the primary factor to cause the precision attenuation of the slide guide. The slide guide of machine tool feeds stochastically in its working process, which leads to the complicated wear behavior of the guide surface. Based on statistical theory, an analytical model of precision retaining ability of slide guide was constructed with analysis of the wear characteristics and accuracy attenuation of slide guide under working conditions. The quantitative relationships between precision retaining ability and its influencing factors, i.e., working condition parameters, running parameters, material property and wear coefficient were described by the model. A test bench of precision retaining ability of slide guides was developed. Bench tests of precision retaining ability with the slide guide samples were conducted to validate the theoretical model. The maximal relative error of experimental results and calculated results were 22%. It indicated that the calculated results fit with the experimental results and the model of precision retaining ability was reasonable. The model can predict the accuracy life of slide guide and it also can provide references for the tribology design and precision retaining design for slide guide.