A dimming system and a dimming converter and load dimming method thereof are provided. In the dimming converter, a cutting phase determination unit is connected with an input terminal and configured to determine phase angle information of a power supply signal of an output of a load terminal in a dimmer; an output unit is configured to output a dimming signal corresponding to the phase angle information determined by the cutting phase determination unit from a dimming output terminal to a load of the dimming system according to a correspondence relationship between the phase angle information and the dimming signal stored in a storage unit and to output a phase-cut power source signal from a supply output terminal to the load. The dimming system can be compatible with a large number of loads with different dimming requirements to thereby improve the dimming efficiency of the loads.