Color ultrasound has no radiation, color ultrasound is mechanical wave not electromagnetic wave, there is no ionizing radiation, color ultrasound examination is generally very safe. However, there is no absolute safety in any examination, and we should look at the problem objectively. When ultrasound propagates in human body, when the sound intensity reaches a certain level, it produces certain biological effects on tissues, including mechanical and thermal effects. When the mechanical and thermal effects reach a certain dose value, it will cause tissue damage. Therefore, for sensitive areas such as early pregnancy fetus or eye examination, mechanical and thermal indices need to be adjusted. To ensure safety, the human operation requires that the examined section should be fixed for a continuous observation time of no more than one minute or after an interval of 2-3 minutes before going to the previous site for observation and reciprocal scanning, which will reduce the average acoustic energy into a certain area of tissue and reduce the biological effect. The power of the instruments used for diagnostic ultrasonography is very low, in fact, there is generally no need to consider the issue of damage to the tissue.