Ultrasound examination has become a routine examination method in clinical diagnosis and treatment of pets，especially in soft tissues such as liver，spleen，heart and kidney. However，due to the complex structure and special location of the liver，it is difficult to diagnose liver diseases by routine ultrasound examination. The contrast? enhanced ultrasound technology has become an important means for the diagnosis of liver diseases in human medicine， but it is rarely used in veterinary clinics. The contrast?enhanced ultrasound has unique advantages，especially in the diagnosis of liver benign and malignant lesions. In this review，we summarized the principle，theoretical basis， clinical application，and research progress of contrast?enhanced ultrasound in the diagnosis of canine liver tumors ．