Abstract: Mud loss is a common problem in drilling fractured formations.To prevent and control lost circulation in these kinds of formations,the causes,characteristic and pattern of drilling fluid loss need to be determined,and the width of in-situ fractures needs to be predicted accurately.Using the approach in reservoir simulation and well testing,drilling fluid loss dynamics model can be established to analyze factors causing mud loss,calculate fracture width with inversion,figure out loss type,characteristic and pattern,providing a new way for lost circulation prevention and control.This paper summed up the progress in the study on mud loss dynamics model,analyzed the advantages and disadvantages of mud loss models,and introduced the application of the models.At last,it was pointed out that mud loss models considering wellbore pressure,fracture network,mud loss model for fracture-vuggy formations are needed to be developed in the future.