The nucleation, grain growth of coarse grains during annealing were tracked using a quasi-in-situ EBSD method. The coarse grains had different orientations and most grains were non-basal orientated. No preferable grain growth or special types of grain boundaries were identified. The main nucleation site of coarse grains was dislocation cells or subgrains in deformed grain interiors. Their recrystallisation behaviour can be illustrated by abnormal subgrain growth (AsGG) rarely reported in Mg alloys. The coarse basal grains showed no growth advantage in terms of grain size or number over other non-basal grains, leading to a weak basal texture in AZ31B alloy.