A method of subblock-based temporal motion vector prediction is performed at a computing device. The computing device acquires a video bitstream including data associated with multiple encoded pictures. While decoding a current picture in the video bitstream, the computing device selects, according to syntax elements signaled in the video bitstream, one reference picture as a collocated picture of the current picture, and determines a temporal vector between the collocated picture and the current picture from motion information of spatially neighboring blocks of a current code unit (CU) according to a fixed order. Next, the computing device splits the current CU into multiple sub-CUs, obtains a temporal motion vector predictor for each sub-CU from the temporal vector and motion information of a block in the collocated picture that corresponds to a respective subblock of the current picture and decodes the current CU according to the temporal motion vector predictors.