A method and apparatus for stroke acquisition, and an ultrasonic electronic stylus are provided. The method is applied to the ultrasonic electronic stylus. In the case that the ultrasonic electronic stylus contacts with a writing board and a pressure generated on the writing board by the ultrasonic electronic stylus reaches a first predetermined value, the ultrasonic electronic stylus is controlled to generate a first signal so that a signal receiver of an electronic device acquires a first stroke based on the first signal. After the first signal is generated, an operation parameter of the ultrasonic electronic stylus is adjusted. In the case that the pressure is smaller than the first predetermined value and a preset condition is satisfied, a second signal is generated so that the electronic device continues to acquire a second stroke based on the second signal.