A high-precision optical interferometer is one of the basic tools for precision measurement, and the ultimate sensitivity of the interferometer is limited by the standard quantum limit (SQL) determined by vacuum fluctuations. By making use of quantum resources, the phase measurement beyond SQL can be realized. In a quantum interferometer based on optical parametric amplifier (OPA), squeezed states produced by OPAs in the two arms are directly used as phase-sensitive quantum states. In addition, the sensitivity of the quantum interferometer can unconditionally surpass SQL by the simultaneous shot noise reduction and amplification of phase-sensitive field intensity. However, quantum states are very sensitive to losses. By analyzing the influence of all kinds of losses on sensitivity, the relationship between sensitivity of the quantum interferometer and losses is obtained. Meanwhile, through analyzing the relationship between sensitivity and other physical parameters such as analysis frequency, the experimental parameters for further optimization of performance including system sensitivity and bandwidth are obtained.