Abstract: The oil reservoirs in Bozhong oilfield are deeper, so there are many deep wells, highly deviated wells and three dimensional wells.In the drilling process of deep wells, many complex situations occur and the rate of penetration is low, which leads to serious casing wear and consequently brings great risks to safe production.Therefore, it is necessary to predict the casing wear and analyze the residual strength.In this paper, a casing wear prediction model for deep wells was established to quantitatively analyze the influence of lateral force, friction stroke and rotational speed on casing wear.In addition, the prediction accuracy was improved significantly by correcting the prediction model through the data measured on site in Bozhong Oilfield.Thus, a casing wear prediction method based on equivalent slip stroke of trip is formed.This method can meet the requirements on the casing wear prediction of deep wells and provide the guidance for casing wear prediction of deep wells in Bozhong Oilfield.