Projection device and safety protection method of projection device

A projection device, comprising a projection lens module, a light source, a light source driving circuit, a storage circuit, a detection unit, and a control circuit, wherein:

• the projection lens module provides a lens identification signal;
• the light source driving circuit is coupled to the light source;
• the storage circuit stores at least one lens information;
• the detection unit detects whether an object enters a detection range of the detection unit and provides a detection result;
• and
• the control circuit is coupled to the projection lens module, the light source driving circuit, the storage circuit, and the detection unit, configured to read corresponding lens information from the at least one lens information in the storage circuit according to the lens identification signal, configured to calculate a warning range according to the lens information, configured to judge whether the object enters the warning range according to the detection result, and configured to control the light source driving circuit to reduce brightness of the light source or turn off the light source in response to the object entering the warning range.