Objective To explore the value of Multi Slice Helical CT(MSCT) in primary knee injury. Methods Sixty cases of suspected knee joint fractures were collected from January 2016 to September2018 in our hospital. After MSCT examination, post-treatment reconstruction was used to adjust the appropriate window width and window level to limit the fractures of the knee joint (including the tiny Fractures), ligament injury, meniscus injury, joint effusion or hemorrhage, soft tissue contusion and so on, the type of knee joint fracture was compared with the surgical pathological results to calculate the diagnostic accuracy, sensitivity, positive predictive value, negative Predictive value. Results Among the 60 cases of knee trauma, there were 10 cases of type Ⅰ, 12 cases of type Ⅱ, 16 cases of type Ⅲ, 5 cases of type Ⅳ, 8 cases of type Ⅴ and 9 cases of type Ⅵ. There were 8 cases of missed diagnosis of X-ray, The accuracy of MSCT was 89.3%, the accuracy of MSCT was 100%, and 12 cases were corrected by MSCT. The sensitivity and specificity of MPR were 88.5% and 93.6% respectively, the positive predictive value was 96.5% and the negative predictive value was 78.6%, which was higher than that of CPR,VR,SSD and MIP (P <0.05). There was no significant difference between MSCT and surgical pathology (P> 0.05). Conclusion Multi-slice spiral CT examination of knee injury, can provide more accurate and clear image information, the clear clinical diagnosis and treatment has a good guiding significance.