We constructed a flexible gold-polydimethylsiloxane (gold-PDMS) nanocomposites film with controllable thickness and light transmittance, to realize optically-excited simultaneous photoacoustic (PA) and ultrasound (US) imaging under a single laser pulse irradiation. Benefiting from the excellent thermoelastic properties, the gold-PDMS film absorbs part of the incident laser energy and produces a high-intensity US, which is used to realize US imaging. Meanwhile, the partly transmitted light is used to excite samples for PA imaging. By controlling the thickness of the gold-PDMS, we can control the center frequency in the US imaging. We experimentally analyzed the frequency of the produced US signal by the gold-PDMS film and compared it with the finite element analysis (FEA) method, where the experiments agree with the FEA results. This method is demonstrated by the experiments on phantoms and a mouse model. Our work provides a cost-effective methodology for simultaneous PA and US imaging.