Device of handling a HARQ retransmission

A communication device for handling a hybrid automatic repeat request (HARQ) retransmission, comprising:

• at least one storage device;
• and
• at least one processing circuit, coupled to the at least one storage device, wherein the at least one storage device stores instructions, and the at least one processing circuit is configured to execute the instructions of:
• receiving a first physical downlink (DL) shared channel (PDSCH) from a network, wherein a first HARQ feedback corresponding to the first PDSCH is allocated in a first uplink (UL) channel and the first UL channel is corresponding to a first priority index;
• determining not to transmit the first HARQ feedback in the first UL channel;
• determining a second UL channel for the first HARQ feedback, wherein the second UL channel is corresponding to a second priority index;
• and
• transmitting the first HARQ feedback in the second UL channel;
• wherein the communication device determines not to transmit the first HARQ feedback, when the first UL channel is collided with a third UL channel and the third UL channel is corresponding to a third priority index higher than the first priority index.