A resource scheduling method and apparatus in a DSL system, and a system are provided, to reduce energy consumption of the DSL system. The method includes: determining, according to service traffic information of each subscriber line and transmission capability information of each subscriber line, a transmission opportunity initial value allocated to each subscriber line in a TDD frame; and according to the transmission opportunity initial value of each subscriber line, dividing the TDD frame into a normal operation interval and a discontinuous operation interval, determining a transmission opportunity occupied by each subscriber line in the normal operation interval, and determining a subscriber line group in the discontinuous operation interval and a transmission opportunity occupied by each subscriber line group in the discontinuous operation interval.