A frame rendering method used in a head-mounted device comprising: receiving a sequence of consecutive input frames (F1, F2, F3); for each two of the consecutive input frames that comprise a first input frame corresponding to a first time spot and a second input frame next to the first input frame and corresponding to a second time spot, performing the steps of: retrieving first orientation information corresponding to the first input frame and second orientation information corresponding to the second input frame from a motion sensor of the head-mounted device; generating predicted orientation information of a predicted orientation corresponding to a target time spot according to the first orientation information and the second orientation information, wherein the target time spot is between the second time spot and a third time spot of a third input frame next to the second input frame; performing orientation calibration on the first input frame according to the first orientation information and the predicted orientation information to generate a first calibrated frame corresponding to the predicted orientation, and performing orientation calibration on the second input frame according to the second orientation information and the predicted orientation information to generate a second calibrated frame corresponding to the predicted orientation; and generating one of a plurality of extrapolated frames according to the first calibrated frame and the second calibrated frame, the one of the extrapolated frames corresponding to the target time spot; wherein the step of generating the one of the extrapolated frames further comprises: performing a motion estimation between the first calibrated frame and the second calibrated frame to generate a motion vector table; and performing a frame extrapolation according to the first calibrated frame and the second calibrated frame based on the motion vector table to generate the one of the extrapolated frames. receiving a sequence of consecutive input frames (F1, F2, F3); for each two of the consecutive input frames that comprise a first input frame corresponding to a first time spot and a second input frame next to the first input frame and corresponding to a second time spot, performing the steps of: retrieving first orientation information corresponding to the first input frame and second orientation information corresponding to the second input frame from a motion sensor of the head-mounted device; generating predicted orientation information of a predicted orientation corresponding to a target time spot according to the first orientation information and the second orientation information, wherein the target time spot is between the second time spot and a third time spot of a third input frame next to the second input frame; performing orientation calibration on the first input frame according to the first orientation information and the predicted orientation information to generate a first calibrated frame corresponding to the predicted orientation, and performing orientation calibration on the second input frame according to the second orientation information and the predicted orientation information to generate a second calibrated frame corresponding to the predicted orientation; and generating one of a plurality of extrapolated frames according to the first calibrated frame and the second calibrated frame, the one of the extrapolated frames corresponding to the target time spot; retrieving first orientation information corresponding to the first input frame and second orientation information corresponding to the second input frame from a motion sensor of the head-mounted device; generating predicted orientation information of a predicted orientation corresponding to a target time spot according to the first orientation information and the second orientation information, wherein the target time spot is between the second time spot and a third time spot of a third input frame next to the second input frame; performing orientation calibration on the first input frame according to the first orientation information and the predicted orientation information to generate a first calibrated frame corresponding to the predicted orientation, and performing orientation calibration on the second input frame according to the second orientation information and the predicted orientation information to generate a second calibrated frame corresponding to the predicted orientation; and generating one of a plurality of extrapolated frames according to the first calibrated frame and the second calibrated frame, the one of the extrapolated frames corresponding to the target time spot; wherein the step of generating the one of the extrapolated frames further comprises: performing a motion estimation between the first calibrated frame and the second calibrated frame to generate a motion vector table; and performing a frame extrapolation according to the first calibrated frame and the second calibrated frame based on the motion vector table to generate the one of the extrapolated frames. performing a motion estimation between the first calibrated frame and the second calibrated frame to generate a motion vector table; and performing a frame extrapolation according to the first calibrated frame and the second calibrated frame based on the motion vector table to generate the one of the extrapolated frames.