A buffer and output method and a buffer module for a multimedia stream are provided, wherein multimedia stream packets are received and stored into a first buffer, and when an actual remaining time calculated according to an accumulated idle time and a buffer time, is greater than a remaining time threshold value, following steps are performed. A first present time is read, and a sleep instruction is executed, so as to wait for a preset idle time. A second present time is read, and an actual idle time different from the preset idle time is calculated according to the first present time and the second present time. A part of buffer units are enabled according to the accumulated idle time accumulated according to the actual idle time, to output the stored multimedia stream packets to a second buffer of a player.