Abstract: A light-adjusting and current-limiting control circuit for a lamp includes a sampling circuit formed of a manganese-copper line or a current transformer, a power circuit provided with resistors, capacitors, diodes, a Varistor and a zener diode, a signal adjusting circuit composed of diodes, resistors, a varistor, triacs and capacitors, and a control output circuit having a thyristor, diodes, a relay and an LED. The control output circuit can be replaced with a light-adjusting input circuit, a chip processor control circuit, a zero-crossing detection circuit and a two-way silicon controlled rectifier control output circuit 5. Thus, the invention has a low cost, a small size and an excellent precision, compared to conventional ones.