Abstract: The thermoelastic generation stress pulse in a semi-infinite strongly absorbing solid when a pulse laser is incident on its surface is studied.The expressions and curves of the ultrasound stress pulse for both free and clamped surfaces are presented.It is shown, theoretically and experimentally,that the ultrasound pulse is monopolar when the sample surface is clamped,and is bipolar when the sample surface free;and the stress pulse almost has the same width as laser pulse.