The utility model relates to an improved timer of a mechanical clock. In the utility model, a normally open contact switch K< 1 > which is composed of movable contact points which are additionally arranged on a uniform machine core alarm setting spring of an alarm clock and corresponding static contact pieces, the alarm hammer component, the alarm head wheel component and the sharp gear component of an alarm clock system are removed, a set of alarm wheel components are additionally arranged, a corresponding normally closed braking switch K< 2 > is arranged, the normally open contact switch K< 1 > and the normally closed braking switch K< 2 > are connected in series with the control circuit of a low voltage DC relay, and the contact head of the relay is used to control an external circuit. The utility model can control the timing conduction of the external circuit and the timing braking of the external circuit, and has the advantages of simple structure, low cost, high safety and practicality. The utility model is suitable for the control of various appliances.