Osteoporosis is a progressive bone disease, which is characterized by a decrease in the bone mass and deterioration in bone micro-architecture. In theory, photoacoustic (PA) analysis has the potential to obtain the characteristics of the bone effectively. In this study, we try to compare the PA spectral analysis (PASA) method with the quantitative ultrasound (QUS) method in osteoporosis assessment. We compare the quantified parameter slope from the PASA and broadband ultrasound attenuation from QUS among different bone models, respectively. Both the simulation and ex vivo experiment results show that bone with lower bone mineral density has the higher slope in the PASA method. Our comparison study proves that the PASA method has the same efficiency as QUS in osteoporosis assessment.