Provided is a variable-capacity mechanism for a scroll compressor. The scroll compressor includes a compression mechanism. The compression mechanism includes a fixed scroll and an orbiting scroll for defining a series of compression cavities. The variable-capacity mechanism includes: a discharge channel, suitable for communicating a medium-pressure compression cavity in the compression cavities with a low-pressure region; blocking members, suitable for selectively opening or closing the discharge channel; an actuation device, including an execution member, the blocking members being connected to the execution member so as to selectively open or close the discharge channel along with the actions of the execution member. Multiple blocking members are connected to a single execution member so as to synchronously move along with the actions of the single execution member. By the variable-capacity mechanism, action synchronization of multiple blocking members can be reliably implemented. Provided is a scroll compressor including the variable-capacity mechanism.