A microscopy scheme is proposed to simultaneously achieve optical scattering-absorption dual-contrast imaging of a transparent or semi-transparent specimen. This scheme is based on a transmission-mode photoacoustic microscope. We find that two peaks exist in the detected photoacoustic signal. One peak is caused by the optical absorption of the specimen, and the other is related to both the optical scattering and absorption of the specimen. Therefore, both the absorption and scattering information can be simultaneously extracted by analyzing the same photoacoustic signal excited by a single-shot laser pulse. After the microscope is validated by imaging a binary mixture consisting of particles with different optical properties, it successfully acquires dual images of red blood cells with different contrasts. Quantitative analysis reveals that the optical absorption and scattering properties of the specimen can be derived from the two images. The proposed dual-modal imaging method would be useful in revealing the structural and functional properties of tissues at the cell level or the clinical assessment of pathological sections.