Objective In this study, we have developed a biodegradable contrast agent for photoacoustic imaging. Its biodegradation products could be fully removed from a living organism. Methods Used light microscope、electron microscope、laser particle size analyzer to test general physical properties and observe stability. Results Nanoparticles were spherical with regular morphology and uniform size distribution, there was no obvious aggregation. The mean particle size of nanoparticles was (230.9±54.58) nm with uniform distribution and dispersion; Zeta potential was (-22.8±5.75) mV. CO2 may be the reason of producing photoacoustic signal. The intensity and the area of the photoacoustic signal enhance corresponding to the increase of concentration, temperature and time. There had no damage to cells by laser. During in vivo test, Serum ammonia concentrations for various treatment groups were higher than that for the control group, but vital signs observation of nude mice shows that there had no significant changes in foraging and movement with respect to the control group. photoacoustic signals were detected from the tumor, reached the peak in 4 h and then disappeared gradually. There was no damage to the skin and subcutaneous tissue by laser radiation. Conclusion It is a gas-generating nanoparticles of liposome encapsulating ammonium bicarbonate solution, and it is safe, effective, cheap and free of side effects.