An angular momentum spinner includes two or more rotating arms loaded with an adjustable sliding block for each arm and laid symmetrically about a rotating center. Each sliding block is controlled to move along the corresponding rotating arm. Such a spinner can display the conservation of angular momentum vividly and intuitively, and can also serve as an amusing toy for children. The spinner can be used as a teaching equipment to demonstrate the theorem of angular momentum conveniently, intuitively and amusingly.