Polydimethylsiloxane/multi-walled carbon nanotube (PDMS/MWCNT) composite had high photoacoustic transduction efficiency owing to its high light absorption coefficient and low interfacial thermal resistance. The high expansion coefficient and light absorption ability of PDMS/MWCNT nanocomposite films have significant positive effects when it is used as a laser ultrasonic transducer. We introduce an ultrasonic-assisted forced impregnation method for the preparation of PDMS/MWCNT nanocomposite films. PDMS was used as the matrix phase, and MWCNTs were used as the nano-supporting framework. PDMS matrix was introduced into the MWCNT framework by the forced impregnation method. The morphology, thermal, and mechanical properties of the nanocomposite film were analyzed systematically. The photoacoustic conversion efficiency was researched through both experiment and simulation methods. The output sound pressure of our PDMS/MWCNT nanocomposite film reached 7.59 MPa when applied as an ultrasonic transducer under the pulsed laser excitation of 1  mJ  /  pulse energy. The photoacoustic conversion efficiency of our sample was 9.98  ×  10^−  4, three times higher than similar products reported before, which offered the possibility to greatly enhance the photoacoustic signals.