Normal menisci show low signal in magnetic resonance T1 and T2 weighted images, and in the sagittal plane, through the body level of the meniscus is a bowtie and through the anterior and posterior corners of the meniscus are sharp triangles; and in the coronal plane, through the body level of the meniscus is a sharp triangle and through the anterior and posterior corners of the meniscus are bowtie shapes. Magnetic resonance is a magnetic resonance phenomenon produced by using hydrogen protons in the human body within a strong external magnetic field and under specific radiofrequency pulses. Depending on the difference in relaxation time between tissues, different tissues exhibit different shades of gray, and the meniscus is fibrocartilage, which exhibits low signals in the T1- and T2-weighted images. The meniscus is divided into the medial meniscus and the lateral meniscus. The medial meniscus is similar to a “C” shape, narrow in the front and wide in the back, and thin in the front and thick in the back; and the lateral meniscus is similar to an “O” shape, with equal heights and widths in each part. In some patients, the lateral meniscus is a congenital discoid meniscus deformity, which is not consistent with the normal meniscus. The specifics need to be considered in the context of the patient’s condition, and the conclusion should be drawn by the clinician after examination, taking into account the imaging data and the patient’s medical history.