An audio playing apparatus and an audio transmission circuit are provided. The audio playing apparatus includes a first audio connector, a second audio connector, a player, and an audio transmission circuit. The second audio connector has a different interface specification than an interface specification of the first audio connector. The audio transmission circuit is coupled to the first audio connector, the second audio connector and the player. The audio transmission circuit detects a power pin of the first audio connector and a power pin of the second audio connector to obtain a determination result, and selects one of the first audio connector and the second audio connector as a target connector according to the determination result, so as to transmit an audio signal associated with the target connector to the player.