A key-retainer with projection light includes key-ring, buckle and pendant hanging together each other; said pendant has a case and connecter, one end of said connecter is hanged together with said key-ring and buckle, another end is connected dismountable with the front end of said case, a lens is set on the rear end of the case; the battery, button and lighter which constitutes the circuit is mounted on the front end in the case in this order, said button is located on the case sidewall and a diaphragm printed with figure & character is set between said lighter and lens. When the button is pressed down, said lighter emits light, the pattern characters on the diaphragm printed with figure & character are projected out through the lens and exert an advertisement influence on masses. The present invention could draw more attentions with better advertisement effects.